/*
* Copyright (c) 2000-2020 Apple Inc. All rights reserved.
*
* This file contains the low-level serial drivers used on ARM/ARM64 devices.
* The generic serial console code in osfmk/console/serial_console.c will call
* into this code to transmit and receive serial data.
*
* Logging can be performed on multiple serial interfaces at once through a
* method called serial multiplexing. This is implemented by enumerating which
* serial interfaces are available on boot and registering them into a linked
* list of interfaces pointed to by gPESF. When outputting or receiving
* characters, each interface is queried in turn.
*
* Please view doc/arm_serial.md for an in-depth description of these drivers.
*/
#include <kern/clock.h>
#include <kern/debug.h>
#include <libkern/OSBase.h>
#include <libkern/section_keywords.h>
#include <mach/mach_time.h>
#include <machine/atomic.h>
#include <machine/machine_routines.h>
#include <pexpert/pexpert.h>
#include <pexpert/protos.h>
#include <pexpert/device_tree.h>
#include <pexpert/arm/consistent_debug.h>
#include <pexpert/arm64/board_config.h>
#include <arm64/proc_reg.h>
#include <pexpert/arm/protos.h>
#include <kern/sched_prim.h>
#ifdef PL011_UART
#include <pexpert/arm/pl011.h>
#endif /* PL011_UART */
#if HIBERNATION
#include <machine/pal_hibernate.h>
#endif /* HIBERNATION */
struct pe_serial_functions {
/* Initialize the underlying serial hardware. */
void (*init) (void);
/* Return a non-zero value if the serial interface is ready to send more data. */
unsigned int (*transmit_ready) (void);
/* Write a single byte of data to serial. */
void (*transmit_data) (uint8_t c);
/* Return a non-zero value if there's a byte of data available. */
unsigned int (*receive_ready) (void);
/* Read a single byte from serial. */
uint8_t (*receive_data) (void);
/* Enables IRQs from this device. */
void (*enable_irq) (void);
/* Disables IRQs from this device and reports whether IRQs were enabled. */
bool (*disable_irq) (void);
/* Clears this device's IRQs targeting this agent, returning true if at least one IRQ was cleared. */
bool (*acknowledge_irq) (void);
/**
* Whether this serial driver can handle irqs. This value should be set by
* querying the device tree to see if the serial device has interrupts
* associated with it.
*
* For a device to support IRQs:
* - enable_irq, disable_irq, and acknowledge_irq must be non-null
* - The AppleSerialShim kext must be able to match to the serial device
* in the IORegistry and call serial_enable_irq with the proper
* serial_device_t
* - The device tree entry for the serial device should have an interrupt
* associated with it.
*/
bool has_irq;
/* enum identifying which serial device these functions belong to. */
serial_device_t device;
/* Pointer to the next serial interface in the linked-list. */
struct pe_serial_functions *next;
};
MARK_AS_HIBERNATE_DATA_CONST_LATE static struct pe_serial_functions* gPESF = NULL;
/**
* Whether uart has been initialized already. This value is kept across a
* sleep/wake cycle so we know we need to reinitialize when serial_init is
* called again after wake.
*/
MARK_AS_HIBERNATE_DATA static bool uart_initted = false;
/* Whether uart should run in simple mode that works during hibernation resume. */
MARK_AS_HIBERNATE_DATA bool uart_hibernation = false;
/** Set <=> transmission is authorized.
* Always set, unless SERIALMODE_ON_DEMAND is provided at boot,
* and no data has yet been received.
* Originaly meant to be a per-pe_serial_functions variable,
* but the data protection on the structs prevents it. */
static bool serial_do_transmit = 1;
/**
* Used to track if all IRQs have been initialized. Each bit of this variable
* represents whether or not a serial device that reports supporting IRQs has
* been initialized yet (1 -> not initialized, 0 -> initialized)
*/
static uint32_t serial_irq_status = 0;
/**
* Set by the 'disable-uart-irq' boot-arg to force serial IRQs into polling mode
* by preventing the serial driver shim kext from registering itself with
* serial_enable_irq.
*/
static bool disable_uart_irq = 0;
static void
register_serial_functions(struct pe_serial_functions *fns)
{
fns->next = gPESF;
gPESF = fns;
}
/**
* Indicates whether or not a given device's irqs have been set up by calling
* serial_enable_irq for that particular device.
*
* @param device_fns Serial functions for the device that is being checked
* @return Whether or not the irqs have been initialized for that device
*/
static bool
irq_initialized(struct pe_serial_functions *device_fns)
{
return (serial_irq_status & device_fns->device) == 0;
}
/**
* Indicates whether or not a given device supports irqs and if they are ready
* to be used.
*
* @param device_fns Serial functions for the device that is being checked
* @return Whether or not the device can and will send IRQs.
*/
static bool
irq_available_and_ready(struct pe_serial_functions *device_fns)
{
return device_fns->has_irq && irq_initialized(device_fns);
}
/**
* Searches through the global serial functions list and returns the serial function for a particular device
*
* @param device The device identifier to search for
* @return Serial functions for the specified device
*/
static struct pe_serial_functions *
get_serial_functions(serial_device_t device)
{
struct pe_serial_functions *fns = gPESF;
while (fns != NULL) {
if (fns->device == device) {
return fns;
}
fns = fns->next;
}
return NULL;
}
/**
* The action to take when polling and waiting for a serial device to be ready
* for output. On ARM64, takes a WFE because the WFE timeout will wake us up in
* the worst case. On ARMv7 devices, we need to hot poll.
*/
static inline void
serial_poll(void)
{
#if __arm64__
if (!uart_hibernation) {
__builtin_arm_wfe();
}
#endif
}
/**
* This ensures that if we have a future product that supports hibernation, but
* doesn't support either UART serial or dock-channels, then hibernation will
* gracefully fall back to the serial method that is supported.
*/
#if HIBERNATION || defined(APPLE_UART)
MARK_AS_HIBERNATE_DATA static volatile apple_uart_registers_t *apple_uart_registers = 0;
#endif /* HIBERNATION || defined(APPLE_UART) */
#if HIBERNATION || defined(DOCKCHANNEL_UART)
MARK_AS_HIBERNATE_DATA static vm_offset_t dockchannel_uart_base = 0;
#endif /* HIBERNATION || defined(DOCKCHANNEL_UART) */
#ifdef PL011_UART
static volatile pl011_registers_t *pl011_registers = NULL;
#endif /* PL011_UART */
/*****************************************************************************/
#ifdef APPLE_UART
static void apple_uart_set_baud_rate(uint32_t baud_rate);
/**
* The Apple UART is configured to use 115200-8-N-1 communication.
*/
static void
apple_uart_init(void)
{
ucon_t ucon = { .raw = 0 };
// Use NCLK (which is constant) instead of PCLK (which is variable).
ucon.clock_selection = UCON_CLOCK_SELECTION_NCLK;
ucon.transmit_mode = UCON_TRANSMIT_MODE_INTERRUPT_OR_POLLING;
ucon.receive_mode = UCON_RECEIVE_MODE_INTERRUPT_OR_POLLING;
ml_io_write32((uintptr_t) &apple_uart_registers->ucon, ucon.raw);
// Configure 8-N-1 communication.
ulcon_t ulcon = { .raw = 0 };
ulcon.word_length = ULCON_WORD_LENGTH_8_BITS;
ulcon.parity_mode = ULCON_PARITY_MODE_NONE;
ulcon.number_of_stop_bits = ULCON_STOP_BITS_1;
ml_io_write32((uintptr_t) &apple_uart_registers->ulcon, ulcon.raw);
apple_uart_set_baud_rate(115200);
// Enable and reset FIFOs.
ufcon_t ufcon = { .raw = 0 };
ufcon.fifo_enable = 1;
ufcon.tx_fifo_reset = 1;
ufcon.rx_fifo_reset = 1;
ml_io_write32((uintptr_t) &apple_uart_registers->ufcon, ufcon.raw);
}
static void
apple_uart_enable_irq(void)
{
// Set the Tx FIFO interrupt trigger level to 0 bytes so interrupts occur when
// the Tx FIFO is completely empty; this leads to higher Tx throughput.
ufcon_t ufcon = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ufcon) };
ufcon.tx_fifo_interrupt_trigger_level_dma_watermark = UFCON_TX_FIFO_ITL_0_BYTES;
ml_io_write32((uintptr_t) &apple_uart_registers->ufcon, ufcon.raw);
// Enable Tx interrupts.
ucon_t ucon = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ucon) };
ucon.transmit_interrupt = 1;
ml_io_write32((uintptr_t) &apple_uart_registers->ucon, ucon.raw);
}
static bool
apple_uart_disable_irq(void)
{
/* Disables Tx interrupts */
ucon_t ucon = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ucon) };
const bool irqs_were_enabled = ucon.transmit_interrupt;
if (irqs_were_enabled) {
ucon.transmit_interrupt = 0;
ml_io_write32((uintptr_t) &apple_uart_registers->ucon, ucon.raw);
}
return irqs_were_enabled;
}
static bool
apple_uart_ack_irq(void)
{
utrstat_t utrstat = { .raw = 0 };
utrstat.transmit_interrupt_status = 1;
ml_io_write32((uintptr_t) &apple_uart_registers->utrstat, utrstat.raw);
return true;
}
static inline bool
apple_uart_fifo_is_empty(void)
{
const ufstat_t ufstat = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ufstat) };
return !(ufstat.tx_fifo_full || ufstat.tx_fifo_count);
}
static void
apple_uart_drain_fifo(void)
{
while (!apple_uart_fifo_is_empty()) {
serial_poll();
}
}
static void
apple_uart_set_baud_rate(uint32_t baud_rate)
{
// Maximum error tolerated from the target baud rate (measured in percentage
// points). Anything greater than this will trigger a kernel panic because
// UART communication will not be reliable.
const float kMaxErrorPercentage = 2.75;
// The acceptable sample rate range; higher sample rates are typically more
// desirable because you can more quickly detect the start bit.
const int kMinSampleRate = 10;
const int kMaxSampleRate = 16;
// Find the first configuration that achieves the target baud rate accuracy,
// starting with the highest sample rate.
const float kSourceClock = gPEClockFrequencyInfo.fix_frequency_hz;
int ubr_div = 0;
int sample_rate = 0;
bool found_configuration = false;
for (int _sample_rate = kMaxSampleRate; _sample_rate >= kMinSampleRate; _sample_rate--) {
const float ideal_ubr_div = (kSourceClock / (baud_rate * _sample_rate)) - 1;
if ((ideal_ubr_div - (int)ideal_ubr_div) < 0.00001f) {
// The ideal baud rate divisor is (basically) attainable.
ubr_div = (int)ideal_ubr_div;
sample_rate = _sample_rate;
found_configuration = true;
break;
} else {
// The ideal baud rate divisor is not attainable; try rounding.
const int ubr_div_rounded_down = (int)ideal_ubr_div;
const int ubr_div_rounded_up = ubr_div_rounded_down + 1;
const float higher_baud_rate = kSourceClock / ((ubr_div_rounded_down + 1) * _sample_rate);
const float lower_baud_rate = kSourceClock / ((ubr_div_rounded_up + 1) * _sample_rate);
if ((((higher_baud_rate - baud_rate) / baud_rate) * 100) < kMaxErrorPercentage) {
ubr_div = ubr_div_rounded_down;
sample_rate = _sample_rate;
found_configuration = true;
break;
}
if ((((baud_rate - lower_baud_rate) / baud_rate) * 100) < kMaxErrorPercentage) {
ubr_div = ubr_div_rounded_up;
sample_rate = _sample_rate;
found_configuration = true;
break;
}
}
}
if (!found_configuration) {
panic("Unable to find a configuration for the UART that would result in a nominal baud rate close enough to %u", baud_rate);
}
// Found an acceptable configuration; write this to the register.
ubrdiv_t ubrdiv = { .raw = 0 };
ubrdiv.sample_rate = 16 - sample_rate;
assert((0 <= ubr_div) && (ubr_div <= UINT16_MAX));
ubrdiv.ubr_div = ubr_div;
ml_io_write32((uintptr_t) &apple_uart_registers->ubrdiv, ubrdiv.raw);
}
MARK_AS_HIBERNATE_TEXT static unsigned int
apple_uart_transmit_ready(void)
{
ufstat_t ufstat = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ufstat) };
return !ufstat.tx_fifo_full;
}
MARK_AS_HIBERNATE_TEXT static void
apple_uart_transmit_data(uint8_t c)
{
utxh_t utxh = { .txdata = c };
ml_io_write32((uintptr_t) &apple_uart_registers->utxh, utxh.raw);
}
static unsigned int
apple_uart_receive_ready(void)
{
ufstat_t ufstat = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->ufstat) };
return ufstat.rx_fifo_full || ufstat.rx_fifo_count;
}
static uint8_t
apple_uart_receive_data(void)
{
urxh_t urxh = { .raw = ml_io_read32((uintptr_t) &apple_uart_registers->urxh) };
return urxh.rxdata;
}
MARK_AS_HIBERNATE_DATA_CONST_LATE
static struct pe_serial_functions apple_serial_functions =
{
.init = apple_uart_init,
.transmit_ready = apple_uart_transmit_ready,
.transmit_data = apple_uart_transmit_data,
.receive_ready = apple_uart_receive_ready,
.receive_data = apple_uart_receive_data,
.enable_irq = apple_uart_enable_irq,
.disable_irq = apple_uart_disable_irq,
.acknowledge_irq = apple_uart_ack_irq,
.device = SERIAL_APPLE_UART
};
static void
apple_uart_setup(const DeviceTreeNode *const devicetree_node)
{
// Get the physical address range of the Apple UART register block.
const struct {
uint64_t block_offset; // TODO: make this scale with #address-cells
uint64_t block_size; // TODO: make this scale with #size-cells
} *reg;
unsigned int reg_size;
if (SecureDTGetProperty(devicetree_node, "reg", (const void **)®, ®_size) != kSuccess) {
panic("Unable to find the 'reg' property on the Apple UART devicetree node");
}
assert(reg_size == sizeof(*reg));
// Create a virtual mapping to that physical address range.
const vm_offset_t soc_base_phys = pe_arm_get_soc_base_phys();
apple_uart_registers = (apple_uart_registers_t *)ml_io_map(soc_base_phys + reg->block_offset, reg->block_size);
// Check if interrupts are supported.
const void *unused;
unsigned int unused_size;
if (SecureDTGetProperty(devicetree_node, "interrupts", &unused, &unused_size) == kSuccess) {
apple_serial_functions.has_irq = true;
}
// Register the Apple UART serial driver.
register_serial_functions(&apple_serial_functions);
}
#endif /* APPLE_UART */
/*****************************************************************************/
#ifdef DOCKCHANNEL_UART
#define DOCKCHANNEL_WR_MAX_STALL_US (30*1000)
static vm_offset_t dock_agent_base;
static uint32_t max_dockchannel_drain_period;
static uint64_t dockchannel_drain_deadline; // Deadline for external agent to drain before a software drain occurs
static bool use_sw_drain;
static uint32_t dock_wstat_mask;
static uint64_t prev_dockchannel_spaces; // Previous w_stat level of the DockChannel.
static uint64_t dockchannel_stall_grace;
MARK_AS_HIBERNATE_DATA static bool use_sw_drain;
MARK_AS_HIBERNATE_DATA static uint32_t dock_wstat_mask;
// forward reference
static struct pe_serial_functions dockchannel_serial_functions;
//=======================
// Local funtions
//=======================
static void
dockchannel_setup(const DeviceTreeNode *const devicetree_node)
{
// Get the physical address ranges of the Dock Channels register blocks.
const struct {
uint64_t channels_block_offset; // TODO: make this scale with #address-cells
uint64_t channels_block_size; // TODO: make this scale with #size-cells
uint64_t agents_block_offset; // TODO: make this scale with #address-cells
uint64_t agents_block_size; // TODO: make this scale with #size-cells
} *reg;
unsigned int reg_size;
if (SecureDTGetProperty(devicetree_node, "reg", (const void **)®, ®_size) != kSuccess) {
panic("Unable to find the 'reg' property on the Dock Channels devicetree node");
}
assert(reg_size == sizeof(*reg));
// Create virtual mappings for those physical address rangess.
const vm_offset_t soc_base_phys = pe_arm_get_soc_base_phys();
dockchannel_uart_base = ml_io_map(soc_base_phys + reg->channels_block_offset, reg->channels_block_size);
dock_agent_base = ml_io_map(soc_base_phys + reg->agents_block_offset, reg->agents_block_size);
// Configure various Dock Channels settings.
const uint32_t *max_aop_clk;
unsigned int max_aop_clk_size;
if (SecureDTGetProperty(devicetree_node, "max-aop-clk", (const void **)&max_aop_clk, &max_aop_clk_size) == kSuccess) {
assert(max_aop_clk_size == sizeof(*max_aop_clk));
max_dockchannel_drain_period = (uint32_t)(*max_aop_clk * 0.03);
} else {
max_dockchannel_drain_period = (uint32_t)DOCKCHANNEL_DRAIN_PERIOD;
}
const uint32_t *enable_sw_drain;
unsigned int enable_sw_drain_size;
if (SecureDTGetProperty(devicetree_node, "enable-sw-drain", (const void **)&enable_sw_drain, &enable_sw_drain_size) == kSuccess) {
assert(enable_sw_drain_size == sizeof(*enable_sw_drain));
use_sw_drain = *enable_sw_drain;
} else {
use_sw_drain = 0;
}
const uint32_t *_dock_wstat_mask;
unsigned int dock_wstat_mask_size;
if (SecureDTGetProperty(devicetree_node, "dock-wstat-mask", (const void **)&_dock_wstat_mask, &dock_wstat_mask_size) == kSuccess) {
assert(dock_wstat_mask_size == sizeof(*_dock_wstat_mask));
dock_wstat_mask = *_dock_wstat_mask;
} else {
dock_wstat_mask = 0x1ff;
}
const void *unused;
unsigned int unused_size;
if (SecureDTGetProperty(devicetree_node, "interrupts", &unused, &unused_size) == kSuccess) {
dockchannel_serial_functions.has_irq = true;
}
prev_dockchannel_spaces = rDOCKCHANNELS_DEV_WSTAT(DOCKCHANNEL_UART_CHANNEL) & dock_wstat_mask;
dockchannel_drain_deadline = mach_absolute_time() + dockchannel_stall_grace;
// Register the Dock Channels serial driver.
register_serial_functions(&dockchannel_serial_functions);
}
static int
dockchannel_drain_on_stall()
{
// Called when DockChannel runs out of spaces.
// Check if the DockChannel reader has stalled. If so, empty the DockChannel ourselves.
// Return number of bytes drained.
if (mach_absolute_time() >= dockchannel_drain_deadline) {
// It's been more than DOCKCHANEL_WR_MAX_STALL_US and nobody read from the FIFO
// Drop a character.
(void)rDOCKCHANNELS_DOCK_RDATA1(DOCKCHANNEL_UART_CHANNEL);
os_atomic_inc(&prev_dockchannel_spaces, relaxed);
return 1;
}
return 0;
}
static void
dockchannel_clear_intr(void)
{
rDOCKCHANNELS_AGENT_AP_INTR_CTRL &= ~(0x3);
rDOCKCHANNELS_AGENT_AP_INTR_STATUS |= 0x3;
rDOCKCHANNELS_AGENT_AP_ERR_INTR_CTRL &= ~(0x3);
rDOCKCHANNELS_AGENT_AP_ERR_INTR_STATUS |= 0x3;
}
static bool
dockchannel_disable_irq(void)
{
const uint32_t ap_intr_ctrl = rDOCKCHANNELS_AGENT_AP_INTR_CTRL;
const bool irqs_were_enabled = ap_intr_ctrl & 0x1;
if (irqs_were_enabled) {
rDOCKCHANNELS_AGENT_AP_INTR_CTRL = ap_intr_ctrl & ~(0x1);
}
return irqs_were_enabled;
}
static void
dockchannel_enable_irq(void)
{
// set interrupt to be when fifo has 255 empty
rDOCKCHANNELS_DEV_WR_WATERMARK(DOCKCHANNEL_UART_CHANNEL) = 0xFF;
rDOCKCHANNELS_AGENT_AP_INTR_CTRL |= 0x1;
}
static bool
dockchannel_ack_irq(void)
{
/* First check if the IRQ is for the kernel */
if (rDOCKCHANNELS_AGENT_AP_INTR_STATUS & 0x1) {
rDOCKCHANNELS_AGENT_AP_INTR_STATUS |= 0x1;
return true;
}
return false;
}
MARK_AS_HIBERNATE_TEXT static void
dockchannel_transmit_data(uint8_t c)
{
rDOCKCHANNELS_DEV_WDATA1(DOCKCHANNEL_UART_CHANNEL) = (unsigned)c;
if (use_sw_drain && !uart_hibernation) {
os_atomic_dec(&prev_dockchannel_spaces, relaxed); // After writing a byte we have one fewer space than previously expected.
}
}
static unsigned int
dockchannel_receive_ready(void)
{
return rDOCKCHANNELS_DEV_RDATA0(DOCKCHANNEL_UART_CHANNEL) & 0x7f;
}
static uint8_t
dockchannel_receive_data(void)
{
return (uint8_t)((rDOCKCHANNELS_DEV_RDATA1(DOCKCHANNEL_UART_CHANNEL) >> 8) & 0xff);
}
MARK_AS_HIBERNATE_TEXT static unsigned int
dockchannel_transmit_ready(void)
{
uint32_t spaces = rDOCKCHANNELS_DEV_WSTAT(DOCKCHANNEL_UART_CHANNEL) & dock_wstat_mask;
if (!uart_hibernation) {
if (use_sw_drain) {
if (spaces > prev_dockchannel_spaces) {
// More spaces showed up. That can only mean someone read the FIFO.
// Note that if the DockFIFO is empty we cannot tell if someone is listening,
// we can only give them the benefit of the doubt.
dockchannel_drain_deadline = mach_absolute_time() + dockchannel_stall_grace;
}
prev_dockchannel_spaces = spaces;
return spaces || dockchannel_drain_on_stall();
}
}
return spaces;
}
static void
dockchannel_init(void)
{
if (use_sw_drain) {
nanoseconds_to_absolutetime(DOCKCHANNEL_WR_MAX_STALL_US * NSEC_PER_USEC, &dockchannel_stall_grace);
}
// Clear all interrupt enable and status bits
dockchannel_clear_intr();
// Setup DRAIN timer
rDOCKCHANNELS_DEV_DRAIN_CFG(DOCKCHANNEL_UART_CHANNEL) = max_dockchannel_drain_period;
// Drain timer doesn't get loaded with value from drain period register if fifo
// is already full. Drop a character from the fifo.
rDOCKCHANNELS_DOCK_RDATA1(DOCKCHANNEL_UART_CHANNEL);
}
MARK_AS_HIBERNATE_DATA_CONST_LATE
static struct pe_serial_functions dockchannel_serial_functions =
{
.init = dockchannel_init,
.transmit_ready = dockchannel_transmit_ready,
.transmit_data = dockchannel_transmit_data,
.receive_ready = dockchannel_receive_ready,
.receive_data = dockchannel_receive_data,
.enable_irq = dockchannel_enable_irq,
.disable_irq = dockchannel_disable_irq,
.acknowledge_irq = dockchannel_ack_irq,
.device = SERIAL_DOCKCHANNEL
};
#endif /* DOCKCHANNEL_UART */
/*****************************************************************************/
#ifdef PL011_UART
static unsigned int
pl011_uart_transmit_ready(void)
{
const uartfr_t uartfr = { .raw = pl011_registers->uartfr.raw };
return uartfr.txff != 1;
}
static void
pl011_uart_transmit_data(uint8_t c)
{
uartdr_t uartdr = { .data = c };
pl011_registers->uartdr.raw = uartdr.raw;
}
static unsigned int
pl011_uart_receive_ready(void)
{
const uartfr_t uartfr = { .raw = pl011_registers->uartfr.raw };
return uartfr.rxfe != 1;
}
static uint8_t
pl011_uart_receive_data(void)
{
const uartdr_t uartdr = { .raw = pl011_registers->uartdr.raw };
return uartdr.data;
}
static void
pl011_uart_init(void)
{
// Before programming the control registers, we must first disable the UART.
// We can accomplish this by manually resetting the UARTCR register.
uartcr_t uartcr = { .raw = 0 };
uartcr.rxe = 1; // This bit's reset value is 1.
uartcr.txe = 1; // This bit's reset value is 1.
pl011_registers->uartcr.raw = uartcr.raw;
// Configure 8-N-1 communication and enable FIFOs.
uartlcr_h_t uartlcr_h = { .raw = 0 };
uartlcr_h.brk = 0;
uartlcr_h.pen = 0;
uartlcr_h.stp2 = 0;
uartlcr_h.fen = 1;
uartlcr_h.wlen = 0b11;
pl011_registers->uartlcr_h.raw = uartlcr_h.raw;
// Re-enable the UART.
uartcr.uarten = 1;
pl011_registers->uartcr.raw = uartcr.raw;
}
SECURITY_READ_ONLY_LATE(static struct pe_serial_functions) pl011_uart_serial_functions =
{
.init = pl011_uart_init,
.transmit_ready = pl011_uart_transmit_ready,
.transmit_data = pl011_uart_transmit_data,
.receive_ready = pl011_uart_receive_ready,
.receive_data = pl011_uart_receive_data,
.device = SERIAL_PL011_UART
};
static void
pl011_uart_setup(const DeviceTreeNode *const devicetree_node)
{
// Get the physical address range of the PL011 UART register block.
const struct {
uint64_t block_offset; // TODO: make this scale with #address-cells
uint64_t block_size; // TODO: make this scale with #size-cells
} *reg;
unsigned int reg_size;
if (SecureDTGetProperty(devicetree_node, "reg", (const void **)®, ®_size) != kSuccess) {
panic("Unable to find the 'reg' property on the PL011 UART devicetree node");
}
assert(reg_size == sizeof(*reg));
// Create a virtual mapping to that physical address range.
const vm_offset_t soc_base_phys = pe_arm_get_soc_base_phys();
pl011_registers = (pl011_registers_t *)ml_io_map(soc_base_phys + reg->block_offset, reg->block_size);
// Register the PL011 UART serial driver.
register_serial_functions(&pl011_uart_serial_functions);
}
#endif /* PL011_UART */
/*****************************************************************************/
/**
* Output @str onto every registered serial interface by polling.
*
* @param str The string to output.
*/
static void uart_puts_force_poll(
const char *str);
/**
* Output @str onto a specific serial interface by polling.
*
* @param str The string to output.
* @param fns The functions to use to output the message.
*/
static void uart_puts_force_poll_device(
const char *str,
struct pe_serial_functions *fns);
#if HIBERNATION
/**
* Transitions the serial driver into a mode that can be run in the hibernation
* resume context. In this mode, the serial driver runs at a barebones level
* without making sure the serial devices are properly initialized or utilizing
* features such as the software drain timer for dockchannels.
*
* Upon the next call to serial_init (once the hibernation image has been
* loaded), this mode is exited and we return to the normal operation of the
* driver.
*/
MARK_AS_HIBERNATE_TEXT void
serial_hibernation_init(void)
{
uart_hibernation = true;
#if defined(APPLE_UART)
apple_uart_registers = (apple_uart_registers_t *)gHibernateGlobals.hibUartRegPhysBase;
#endif /* defined(APPLE_UART) */
#if defined(DOCKCHANNEL_UART)
dockchannel_uart_base = gHibernateGlobals.dockChannelRegPhysBase;
#endif /* defined(DOCKCHANNEL_UART) */
}
/**
* Transitions the serial driver back to non-hibernation mode so it can resume
* normal operations. Should only be called from serial_init on a hibernation
* resume.
*/
MARK_AS_HIBERNATE_TEXT static void
serial_hibernation_cleanup(void)
{
uart_hibernation = false;
#if defined(APPLE_UART)
apple_uart_registers = (apple_uart_registers_t *)gHibernateGlobals.hibUartRegVirtBase;
#endif /* defined(APPLE_UART) */
#if defined(DOCKCHANNEL_UART)
dockchannel_uart_base = gHibernateGlobals.dockChannelRegVirtBase;
#endif /* defined(DOCKCHANNEL_UART) */
}
#endif /* HIBERNATION */
/**
* @brief This array maps "compatible" strings from the devicetree identifying
* different serial device drivers to their corresponding setup functions.
*/
static const struct {
const char *const compatible;
void(*const setup)(const DeviceTreeNode * const devicetree_node);
} driver_setup_functions[] = {
#ifdef APPLE_UART
{ .compatible = "uart-1,samsung", .setup = apple_uart_setup },
#endif // APPLE_UART
#ifdef DOCKCHANNEL_UART
{ .compatible = "aapl,dock-channels", .setup = dockchannel_setup },
#endif // DOCKCHANNEL_UART
#ifdef PL011_UART
{ .compatible = "arm,pl011", .setup = pl011_uart_setup },
#endif // PL011_UART
};
int
serial_init(void)
{
vm_offset_t soc_base;
struct pe_serial_functions *fns = gPESF;
/**
* Even if the serial devices have already been initialized on cold boot,
* when coming out of a sleep/wake, they'll need to be re-initialized. Since
* the uart_initted value is kept across a sleep/wake, always re-initialize
* to be safe.
*/
if (uart_initted) {
#if HIBERNATION
if (uart_hibernation) {
serial_hibernation_cleanup();
}
#endif /* HIBERNATION */
while (fns != NULL) {
fns->init();
fns = fns->next;
}
return gPESF != NULL;
}
soc_base = pe_arm_get_soc_base_phys();
if (soc_base == 0) {
uart_initted = true;
return 0;
}
PE_parse_boot_argn("disable-uart-irq", &disable_uart_irq, sizeof(disable_uart_irq));
// Check the "defaults" devicetree node to see whether or not a serial
// device was specified. Specifically, check for the presence of a
// "serial-device" phandle property.
const DeviceTreeNode *defaults_node;
if (SecureDTFindNodeWithStringProperty("name", "defaults", &defaults_node) != kSuccess) {
panic("Unable to find the 'defaults' devicetree node.");
}
bool serial_device_phandle_specified = false;
const uint32_t *phandle;
unsigned int phandle_size;
if (SecureDTGetProperty(defaults_node, "serial-device", (const void **)&phandle, &phandle_size) == kSuccess) {
assert(phandle_size == sizeof(*phandle));
serial_device_phandle_specified = true;
}
// Allow people to manually specify a serial device phandle via bootarg.
uint32_t phandle_bootarg;
if (PE_parse_boot_argn("serial-device", &phandle_bootarg, sizeof(phandle_bootarg))) {
phandle = &phandle_bootarg;
serial_device_phandle_specified = true;
}
// Return early if no serial device phandle was specified either in the
// devicetree or via bootarg.
if (!serial_device_phandle_specified) {
return 0;
}
// Look at the "compatible" string in the devicetree node referenced by the
// "serial-device" phandle property to see which driver we should use.
const DeviceTreeNode *serial_device_node;
if (SecureDTFindNodeWithPhandle(*phandle, &serial_device_node) != kSuccess) {
panic("Unable to find a devicetree node with phandle %x", *phandle);
}
const char *compatible;
unsigned int compatible_size;
if (SecureDTGetProperty(serial_device_node, "compatible", (const void **)&compatible, &compatible_size) != kSuccess) {
panic("The serial device devicetree node doesn't have a 'compatible' string");
}
// Call the setup function for the identified serial device driver.
bool found_matching_driver = false;
const int n_drivers = sizeof(driver_setup_functions) / sizeof(driver_setup_functions[0]);
for (int i = 0; i < n_drivers; i++) {
if (strcmp(compatible, driver_setup_functions[i].compatible) == 0) {
found_matching_driver = true;
driver_setup_functions[i].setup(serial_device_node);
}
}
if (!found_matching_driver) {
panic("Unable to find serial device driver for '%s'", compatible);
}
fns = gPESF;
while (fns != NULL) {
serial_do_transmit = 1;
fns->init();
if (fns->has_irq) {
serial_irq_status |= fns->device; // serial_device_t is one-hot
}
fns = fns->next;
}
#if HIBERNATION
/* hibernation needs to know the UART register addresses since it can't directly use this serial driver */
if (dockchannel_uart_base) {
gHibernateGlobals.dockChannelRegPhysBase = ml_vtophys(dockchannel_uart_base);
gHibernateGlobals.dockChannelRegVirtBase = dockchannel_uart_base;
gHibernateGlobals.dockChannelWstatMask = dock_wstat_mask;
}
if (apple_uart_registers) {
gHibernateGlobals.hibUartRegPhysBase = ml_vtophys((vm_offset_t)apple_uart_registers);
gHibernateGlobals.hibUartRegVirtBase = (vm_offset_t)apple_uart_registers;
}
#endif /* HIBERNATION */
/* Complete. */
uart_initted = true;
return gPESF != NULL;
}
/**
* Forbid or allow transmission over each serial until they receive data.
*/
void
serial_set_on_demand(bool on_demand)
{
/* Enable or disable transmission. */
serial_do_transmit = !on_demand;
/* If on-demand is enabled, report it. */
if (on_demand) {
uart_puts_force_poll(
"On-demand serial mode selected.\n"
"Waiting for user input to send logs.\n"
);
}
}
/**
* Returns a deadline for the longest time the serial driver should wait for an
* interrupt for. This serves as a timeout for the IRQ to allow for the software
* drain timer that dockchannels supports.
*
* @param fns serial functions representing the device to find the deadline for
*
* @returns absolutetime deadline for this device's IRQ.
*/
static uint64_t
serial_interrupt_deadline(__unused struct pe_serial_functions *fns)
{
#if defined(DOCKCHANNEL_UART)
if (fns->device == SERIAL_DOCKCHANNEL && use_sw_drain) {
return dockchannel_drain_deadline;
}
#endif
/**
* Default to 1.5ms for all other devices. 1.5ms was chosen as the baudrate
* of the AppleSerialDevice is 115200, meaning that it should only take
* ~1.5ms to drain the 16 character buffer completely.
*/
uint64_t timeout_interval;
nanoseconds_to_absolutetime(1500 * NSEC_PER_USEC, &timeout_interval);
return mach_absolute_time() + timeout_interval;
}
/**
* Goes to sleep waiting for an interrupt from a specificed serial device.
*
* @param fns serial functions representing the device to wait for
*/
static void
serial_wait_for_interrupt(struct pe_serial_functions *fns)
{
/**
* This block of code is set up to avoid a race condition in which the IRQ
* is transmitted and processed by IOKit in between the time we check if the
* device is ready to transmit and when we call thread_block. If the IRQ
* fires in that time, thread_wakeup may have already been called in which
* case we would be blocking and have nothing to wake us up.
*
* To avoid this issue, we first call assert_wait_deadline, which prepares
* the thread to be blocked, but does not actually block the thread. After
* this point, any call to thread_wakeup from IRQ handler will prevent
* thread_block from actually blocking. As a performance optimization, we
* then double check if the device is ready to transmit and if it is, then
* we cancel the wait and just continue normally.
*/
assert_wait_deadline(fns, THREAD_UNINT, serial_interrupt_deadline(fns));
if (!fns->transmit_ready()) {
fns->enable_irq();
thread_block(THREAD_CONTINUE_NULL);
} else {
clear_wait(current_thread(), THREAD_AWAKENED);
}
}
/**
* Transmit a character over the specified serial output device.
*
* @param c Character to send
* @param poll Whether we should poll or wait for an interrupt.
* @param force Whether we should force this over the device if output has not been enabled yet.
* @param fns Functions for the device to output over.
*/
static inline void
uart_putc_device(char c, bool poll, bool force, struct pe_serial_functions *fns)
{
if (!(serial_do_transmit || force)) {
return;
}
while (!fns->transmit_ready()) {
if (irq_available_and_ready(fns) && !poll) {
serial_wait_for_interrupt(fns);
} else {
serial_poll();
}
}
fns->transmit_data((uint8_t)c);
}
/**
* Output a character onto every registered serial interface whose
* transmission is enabled..
*
* @param c The character to output.
* @param poll Whether the driver should poll to send the character or if it can
* wait for an interrupt
*/
MARK_AS_HIBERNATE_TEXT void
uart_putc_options(char c, bool poll)
{
struct pe_serial_functions *fns = gPESF;
while (fns != NULL) {
uart_putc_device(c, poll, false, fns);
fns = fns->next;
}
}
/**
* Output a character onto every registered serial interface whose
* transmission is enabled by polling.
*
* @param c The character to output.
*/
void
uart_putc(char c)
{
uart_putc_options(c, true);
}
/**
* Output @str onto every registered serial interface by polling.
*
* @param str The string to output.
*/
static void
uart_puts_force_poll(
const char *str)
{
struct pe_serial_functions *fns = gPESF;
while (fns != NULL) {
uart_puts_force_poll_device(str, fns);
fns = fns->next;
}
}
/**
* Output @str onto a specific serial interface by polling.
*
* @param str The string to output.
* @param fns The functions to use to output the message.
*/
static void
uart_puts_force_poll_device(
const char *str,
struct pe_serial_functions *fns)
{
char c;
while ((c = *(str++))) {
uart_putc_device(c, true, true, fns);
}
}
/**
* Read a character from the first registered serial interface that has data
* available.
*
* @return The character if any interfaces have data available, otherwise -1.
*/
int
uart_getc(void)
{
struct pe_serial_functions *fns = gPESF;
while (fns != NULL) {
if (fns->receive_ready()) {
serial_do_transmit = 1;
return (int)fns->receive_data();
}
fns = fns->next;
}
return -1;
}
/**
* Enables IRQs for a specific serial device and returns whether or not IRQs for
* that device where enabled successfully. For a serial driver to have irqs
* enabled, it must have the enable_irq, disable_irq, and acknowledge_irq
* functions defined and the has_irq flag set.
*
* @param device Serial device to enable irqs on
* @note This function should only be called from the AppleSerialShim kext
*/
kern_return_t
serial_irq_enable(serial_device_t device)
{
struct pe_serial_functions *fns = get_serial_functions(device);
if (!fns || !fns->has_irq || disable_uart_irq) {
return KERN_FAILURE;
}
serial_irq_status &= ~device;
return KERN_SUCCESS;
}
/**
* Performs any actions needed to handle this IRQ. Wakes up the thread waiting
* on the interrupt if one exists.
*
* @param device Serial device that generated the IRQ.
* @note Interrupts will have already been cleared and disabled by serial_irq_filter.
* @note This function should only be called from the AppleSerialShim kext.
*/
kern_return_t
serial_irq_action(serial_device_t device)
{
struct pe_serial_functions *fns = get_serial_functions(device);
if (!fns || !fns->has_irq) {
return KERN_FAILURE;
}
/**
* Because IRQs are enabled only when we know a thread is about to sleep, we
* can call wake up and reasonably expect there to be a thread waiting.
*/
thread_wakeup(fns);
return KERN_SUCCESS;
}
/**
* Returns true if the pending IRQ for device is one that can be handled by the
* platform serial driver.
*
* @param device Serial device that generated the IRQ.
* @note This function is called from a primary interrupt context and should be
* kept lightweight.
* @note This function should only be called from the AppleSerialShim kext
*/
bool
serial_irq_filter(serial_device_t device)
{
struct pe_serial_functions *fns = get_serial_functions(device);
if (!fns || !fns->has_irq) {
return false;
}
/**
* Disable IRQs until next time a thread waits for an interrupt to prevent an interrupt storm.
*/
const bool had_irqs_enabled = fns->disable_irq();
const bool was_our_interrupt = fns->acknowledge_irq();
/* Re-enable IRQs if the interrupt wasn't for us. */
if (had_irqs_enabled && !was_our_interrupt) {
fns->enable_irq();
}
return was_our_interrupt;
}
/**
* Prepares all serial devices to go to sleep by draining the hardware FIFOs
* and disabling interrupts.
*/
void
serial_go_to_sleep(void)
{
struct pe_serial_functions *fns = gPESF;
while (fns != NULL) {
if (irq_available_and_ready(fns)) {
fns->disable_irq();
}
fns = fns->next;
}
#ifdef APPLE_UART
/* APPLE_UART needs to drain FIFO before sleeping */
if (get_serial_functions(SERIAL_APPLE_UART)) {
apple_uart_drain_fifo();
}
#endif /* APPLE_UART */
}