// SPDX-License-Identifier: GPL-2.0
/*
* TTY driver for MIPS EJTAG Fast Debug Channels.
*
* Copyright (C) 2007-2015 Imagination Technologies Ltd
*/
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kgdb.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/uaccess.h>
#include <asm/cdmm.h>
#include <asm/irq.h>
/* Register offsets */
#define REG_FDACSR 0x00 /* FDC Access Control and Status Register */
#define REG_FDCFG 0x08 /* FDC Configuration Register */
#define REG_FDSTAT 0x10 /* FDC Status Register */
#define REG_FDRX 0x18 /* FDC Receive Register */
#define REG_FDTX(N) (0x20+0x8*(N)) /* FDC Transmit Register n (0..15) */
/* Register fields */
#define REG_FDCFG_TXINTTHRES_SHIFT 18
#define REG_FDCFG_TXINTTHRES (0x3 << REG_FDCFG_TXINTTHRES_SHIFT)
#define REG_FDCFG_TXINTTHRES_DISABLED (0x0 << REG_FDCFG_TXINTTHRES_SHIFT)
#define REG_FDCFG_TXINTTHRES_EMPTY (0x1 << REG_FDCFG_TXINTTHRES_SHIFT)
#define REG_FDCFG_TXINTTHRES_NOTFULL (0x2 << REG_FDCFG_TXINTTHRES_SHIFT)
#define REG_FDCFG_TXINTTHRES_NEAREMPTY (0x3 << REG_FDCFG_TXINTTHRES_SHIFT)
#define REG_FDCFG_RXINTTHRES_SHIFT 16
#define REG_FDCFG_RXINTTHRES (0x3 << REG_FDCFG_RXINTTHRES_SHIFT)
#define REG_FDCFG_RXINTTHRES_DISABLED (0x0 << REG_FDCFG_RXINTTHRES_SHIFT)
#define REG_FDCFG_RXINTTHRES_FULL (0x1 << REG_FDCFG_RXINTTHRES_SHIFT)
#define REG_FDCFG_RXINTTHRES_NOTEMPTY (0x2 << REG_FDCFG_RXINTTHRES_SHIFT)
#define REG_FDCFG_RXINTTHRES_NEARFULL (0x3 << REG_FDCFG_RXINTTHRES_SHIFT)
#define REG_FDCFG_TXFIFOSIZE_SHIFT 8
#define REG_FDCFG_TXFIFOSIZE (0xff << REG_FDCFG_TXFIFOSIZE_SHIFT)
#define REG_FDCFG_RXFIFOSIZE_SHIFT 0
#define REG_FDCFG_RXFIFOSIZE (0xff << REG_FDCFG_RXFIFOSIZE_SHIFT)
#define REG_FDSTAT_TXCOUNT_SHIFT 24
#define REG_FDSTAT_TXCOUNT (0xff << REG_FDSTAT_TXCOUNT_SHIFT)
#define REG_FDSTAT_RXCOUNT_SHIFT 16
#define REG_FDSTAT_RXCOUNT (0xff << REG_FDSTAT_RXCOUNT_SHIFT)
#define REG_FDSTAT_RXCHAN_SHIFT 4
#define REG_FDSTAT_RXCHAN (0xf << REG_FDSTAT_RXCHAN_SHIFT)
#define REG_FDSTAT_RXE BIT(3) /* Rx Empty */
#define REG_FDSTAT_RXF BIT(2) /* Rx Full */
#define REG_FDSTAT_TXE BIT(1) /* Tx Empty */
#define REG_FDSTAT_TXF BIT(0) /* Tx Full */
/* Default channel for the early console */
#define CONSOLE_CHANNEL 1
#define NUM_TTY_CHANNELS 16
#define RX_BUF_SIZE 1024
/*
* When the IRQ is unavailable, the FDC state must be polled for incoming data
* and space becoming available in TX FIFO.
*/
#define FDC_TTY_POLL (HZ / 50)
struct mips_ejtag_fdc_tty;
/**
* struct mips_ejtag_fdc_tty_port - Wrapper struct for FDC tty_port.
* @port: TTY port data
* @driver: TTY driver.
* @rx_lock: Lock for rx_buf.
* This protects between the hard interrupt and user
* context. It's also held during read SWITCH operations.
* @rx_buf: Read buffer.
* @xmit_lock: Lock for xmit_*, and port.xmit_buf.
* This protects between user context and kernel thread.
* It is used from chars_in_buffer()/write_room() TTY
* callbacks which are used during wait operations, so a
* mutex is unsuitable.
* @xmit_cnt: Size of xmit buffer contents.
* @xmit_head: Head of xmit buffer where data is written.
* @xmit_tail: Tail of xmit buffer where data is read.
* @xmit_empty: Completion for xmit buffer being empty.
*/
struct mips_ejtag_fdc_tty_port {
struct tty_port port;
struct mips_ejtag_fdc_tty *driver;
raw_spinlock_t rx_lock;
void *rx_buf;
spinlock_t xmit_lock;
unsigned int xmit_cnt;
unsigned int xmit_head;
unsigned int xmit_tail;
struct completion xmit_empty;
};
/**
* struct mips_ejtag_fdc_tty - Driver data for FDC as a whole.
* @dev: FDC device (for dev_*() logging).
* @driver: TTY driver.
* @cpu: CPU number for this FDC.
* @fdc_name: FDC name (not for base of channel names).
* @driver_name: Base of driver name.
* @ports: Per-channel data.
* @waitqueue: Wait queue for waiting for TX data, or for space in TX
* FIFO.
* @lock: Lock to protect FDCFG (interrupt enable).
* @thread: KThread for writing out data to FDC.
* @reg: FDC registers.
* @tx_fifo: TX FIFO size.
* @xmit_size: Size of each port's xmit buffer.
* @xmit_total: Total number of bytes (from all ports) to transmit.
* @xmit_next: Next port number to transmit from (round robin).
* @xmit_full: Indicates TX FIFO is full, we're waiting for space.
* @irq: IRQ number (negative if no IRQ).
* @removing: Indicates the device is being removed and @poll_timer
* should not be restarted.
* @poll_timer: Timer for polling for interrupt events when @irq < 0.
* @sysrq_pressed: Whether the magic sysrq key combination has been
* detected. See mips_ejtag_fdc_handle().
*/
struct mips_ejtag_fdc_tty {
struct device *dev;
struct tty_driver *driver;
unsigned int cpu;
char fdc_name[16];
char driver_name[16];
struct mips_ejtag_fdc_tty_port ports[NUM_TTY_CHANNELS];
wait_queue_head_t waitqueue;
raw_spinlock_t lock;
struct task_struct *thread;
void __iomem *reg;
u8 tx_fifo;
unsigned int xmit_size;
atomic_t xmit_total;
unsigned int xmit_next;
bool xmit_full;
int irq;
bool removing;
struct timer_list poll_timer;
#ifdef CONFIG_MAGIC_SYSRQ
bool sysrq_pressed;
#endif
};
/* Hardware access */
static inline void mips_ejtag_fdc_write(struct mips_ejtag_fdc_tty *priv,
unsigned int offs, unsigned int data)
{
__raw_writel(data, priv->reg + offs);
}
static inline unsigned int mips_ejtag_fdc_read(struct mips_ejtag_fdc_tty *priv,
unsigned int offs)
{
return __raw_readl(priv->reg + offs);
}
/* Encoding of byte stream in FDC words */
/**
* struct fdc_word - FDC word encoding some number of bytes of data.
* @word: Raw FDC word.
* @bytes: Number of bytes encoded by @word.
*/
struct fdc_word {
u32 word;
unsigned int bytes;
};
/*
* This is a compact encoding which allows every 1 byte, 2 byte, and 3 byte
* sequence to be encoded in a single word, while allowing the majority of 4
* byte sequences (including all ASCII and common binary data) to be encoded in
* a single word too.
* _______________________ _____________
* | FDC Word | |
* |31-24|23-16|15-8 | 7-0 | Bytes |
* |_____|_____|_____|_____|_____________|
* | | | | | |
* |0x80 |0x80 |0x80 | WW | WW |
* |0x81 |0x81 | XX | WW | WW XX |
* |0x82 | YY | XX | WW | WW XX YY |
* | ZZ | YY | XX | WW | WW XX YY ZZ |
* |_____|_____|_____|_____|_____________|
*
* Note that the 4-byte encoding can only be used where none of the other 3
* encodings match, otherwise it must fall back to the 3 byte encoding.
*/
/* ranges >= 1 && sizes[0] >= 1 */
static struct fdc_word mips_ejtag_fdc_encode(const char **ptrs,
unsigned int *sizes,
unsigned int ranges)
{
struct fdc_word word = { 0, 0 };
const char **ptrs_end = ptrs + ranges;
for (; ptrs < ptrs_end; ++ptrs) {
const char *ptr = *(ptrs++);
const char *end = ptr + *(sizes++);
for (; ptr < end; ++ptr) {
word.word |= (u8)*ptr << (8*word.bytes);
++word.bytes;
if (word.bytes == 4)
goto done;
}
}
done:
/* Choose the appropriate encoding */
switch (word.bytes) {
case 4:
/* 4 byte encoding, but don't match the 1-3 byte encodings */
if ((word.word >> 8) != 0x808080 &&
(word.word >> 16) != 0x8181 &&
(word.word >> 24) != 0x82)
break;
/* Fall back to a 3 byte encoding */
word.bytes = 3;
word.word &= 0x00ffffff;
fallthrough;
case 3:
/* 3 byte encoding */
word.word |= 0x82000000;
break;
case 2:
/* 2 byte encoding */
word.word |= 0x81810000;
break;
case 1:
/* 1 byte encoding */
word.word |= 0x80808000;
break;
}
return word;
}
static unsigned int mips_ejtag_fdc_decode(u32 word, char *buf)
{
buf[0] = (u8)word;
word >>= 8;
if (word == 0x808080)
return 1;
buf[1] = (u8)word;
word >>= 8;
if (word == 0x8181)
return 2;
buf[2] = (u8)word;
word >>= 8;
if (word == 0x82)
return 3;
buf[3] = (u8)word;
return 4;
}
/* Console operations */
/**
* struct mips_ejtag_fdc_console - Wrapper struct for FDC consoles.
* @cons: Console object.
* @tty_drv: TTY driver associated with this console.
* @lock: Lock to protect concurrent access to other fields.
* This is raw because it may be used very early.
* @initialised: Whether the console is initialised.
* @regs: Registers base address for each CPU.
*/
struct mips_ejtag_fdc_console {
struct console cons;
struct tty_driver *tty_drv;
raw_spinlock_t lock;
bool initialised;
void __iomem *regs[NR_CPUS];
};
/* Low level console write shared by early console and normal console */
static void mips_ejtag_fdc_console_write(struct console *c, const char *s,
unsigned int count)
{
struct mips_ejtag_fdc_console *cons =
container_of(c, struct mips_ejtag_fdc_console, cons);
void __iomem *regs;
struct fdc_word word;
unsigned long flags;
unsigned int i, buf_len, cpu;
bool done_cr = false;
char buf[4];
const char *buf_ptr = buf;
/* Number of bytes of input data encoded up to each byte in buf */
u8 inc[4];
local_irq_save(flags);
cpu = smp_processor_id();
regs = cons->regs[cpu];
/* First console output on this CPU? */
if (!regs) {
regs = mips_cdmm_early_probe(0xfd);
cons->regs[cpu] = regs;
}
/* Already tried and failed to find FDC on this CPU? */
if (IS_ERR(regs))
goto out;
while (count) {
/*
* Copy the next few characters to a buffer so we can inject
* carriage returns before newlines.
*/
for (buf_len = 0, i = 0; buf_len < 4 && i < count; ++buf_len) {
if (s[i] == '\n' && !done_cr) {
buf[buf_len] = '\r';
done_cr = true;
} else {
buf[buf_len] = s[i];
done_cr = false;
++i;
}
inc[buf_len] = i;
}
word = mips_ejtag_fdc_encode(&buf_ptr, &buf_len, 1);
count -= inc[word.bytes - 1];
s += inc[word.bytes - 1];
/* Busy wait until there's space in fifo */
while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
;
__raw_writel(word.word, regs + REG_FDTX(c->index));
}
out:
local_irq_restore(flags);
}
static struct tty_driver *mips_ejtag_fdc_console_device(struct console *c,
int *index)
{
struct mips_ejtag_fdc_console *cons =
container_of(c, struct mips_ejtag_fdc_console, cons);
*index = c->index;
return cons->tty_drv;
}
/* Initialise an FDC console (early or normal */
static int __init mips_ejtag_fdc_console_init(struct mips_ejtag_fdc_console *c)
{
void __iomem *regs;
unsigned long flags;
int ret = 0;
raw_spin_lock_irqsave(&c->lock, flags);
/* Don't init twice */
if (c->initialised)
goto out;
/* Look for the FDC device */
regs = mips_cdmm_early_probe(0xfd);
if (IS_ERR(regs)) {
ret = PTR_ERR(regs);
goto out;
}
c->initialised = true;
c->regs[smp_processor_id()] = regs;
register_console(&c->cons);
out:
raw_spin_unlock_irqrestore(&c->lock, flags);
return ret;
}
static struct mips_ejtag_fdc_console mips_ejtag_fdc_con = {
.cons = {
.name = "fdc",
.write = mips_ejtag_fdc_console_write,
.device = mips_ejtag_fdc_console_device,
.flags = CON_PRINTBUFFER,
.index = -1,
},
.lock = __RAW_SPIN_LOCK_UNLOCKED(mips_ejtag_fdc_con.lock),
};
/* TTY RX/TX operations */
/**
* mips_ejtag_fdc_put_chan() - Write out a block of channel data.
* @priv: Pointer to driver private data.
* @chan: Channel number.
*
* Write a single block of data out to the debug adapter. If the circular buffer
* is wrapped then only the first block is written.
*
* Returns: The number of bytes that were written.
*/
static unsigned int mips_ejtag_fdc_put_chan(struct mips_ejtag_fdc_tty *priv,
unsigned int chan)
{
struct mips_ejtag_fdc_tty_port *dport;
struct tty_struct *tty;
const char *ptrs[2];
unsigned int sizes[2] = { 0 };
struct fdc_word word = { .bytes = 0 };
unsigned long flags;
dport = &priv->ports[chan];
spin_lock(&dport->xmit_lock);
if (dport->xmit_cnt) {
ptrs[0] = dport->port.xmit_buf + dport->xmit_tail;
sizes[0] = min_t(unsigned int,
priv->xmit_size - dport->xmit_tail,
dport->xmit_cnt);
ptrs[1] = dport->port.xmit_buf;
sizes[1] = dport->xmit_cnt - sizes[0];
word = mips_ejtag_fdc_encode(ptrs, sizes, 1 + !!sizes[1]);
dev_dbg(priv->dev, "%s%u: out %08x: \"%*pE%*pE\"\n",
priv->driver_name, chan, word.word,
min_t(int, word.bytes, sizes[0]), ptrs[0],
max_t(int, 0, word.bytes - sizes[0]), ptrs[1]);
local_irq_save(flags);
/* Maybe we raced with the console and TX FIFO is full */
if (mips_ejtag_fdc_read(priv, REG_FDSTAT) & REG_FDSTAT_TXF)
word.bytes = 0;
else
mips_ejtag_fdc_write(priv, REG_FDTX(chan), word.word);
local_irq_restore(flags);
dport->xmit_cnt -= word.bytes;
if (!dport->xmit_cnt) {
/* Reset pointers to avoid wraps */
dport->xmit_head = 0;
dport->xmit_tail = 0;
complete(&dport->xmit_empty);
} else {
dport->xmit_tail += word.bytes;
if (dport->xmit_tail >= priv->xmit_size)
dport->xmit_tail -= priv->xmit_size;
}
atomic_sub(word.bytes, &priv->xmit_total);
}
spin_unlock(&dport->xmit_lock);
/* If we've made more data available, wake up tty */
if (sizes[0] && word.bytes) {
tty = tty_port_tty_get(&dport->port);
if (tty) {
tty_wakeup(tty);
tty_kref_put(tty);
}
}
return word.bytes;
}
/**
* mips_ejtag_fdc_put() - Kernel thread to write out channel data to FDC.
* @arg: Driver pointer.
*
* This kernel thread runs while @priv->xmit_total != 0, and round robins the
* channels writing out blocks of buffered data to the FDC TX FIFO.
*/
static int mips_ejtag_fdc_put(void *arg)
{
struct mips_ejtag_fdc_tty *priv = arg;
struct mips_ejtag_fdc_tty_port *dport;
unsigned int ret;
u32 cfg;
__set_current_state(TASK_RUNNING);
while (!kthread_should_stop()) {
/* Wait for data to actually write */
wait_event_interruptible(priv->waitqueue,
atomic_read(&priv->xmit_total) ||
kthread_should_stop());
if (kthread_should_stop())
break;
/* Wait for TX FIFO space to write data */
raw_spin_lock_irq(&priv->lock);
if (mips_ejtag_fdc_read(priv, REG_FDSTAT) & REG_FDSTAT_TXF) {
priv->xmit_full = true;
if (priv->irq >= 0) {
/* Enable TX interrupt */
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
cfg &= ~REG_FDCFG_TXINTTHRES;
cfg |= REG_FDCFG_TXINTTHRES_NOTFULL;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
}
}
raw_spin_unlock_irq(&priv->lock);
wait_event_interruptible(priv->waitqueue,
!(mips_ejtag_fdc_read(priv, REG_FDSTAT)
& REG_FDSTAT_TXF) ||
kthread_should_stop());
if (kthread_should_stop())
break;
/* Find next channel with data to output */
for (;;) {
dport = &priv->ports[priv->xmit_next];
spin_lock(&dport->xmit_lock);
ret = dport->xmit_cnt;
spin_unlock(&dport->xmit_lock);
if (ret)
break;
/* Round robin */
++priv->xmit_next;
if (priv->xmit_next >= NUM_TTY_CHANNELS)
priv->xmit_next = 0;
}
/* Try writing data to the chosen channel */
ret = mips_ejtag_fdc_put_chan(priv, priv->xmit_next);
/*
* If anything was output, move on to the next channel so as not
* to starve other channels.
*/
if (ret) {
++priv->xmit_next;
if (priv->xmit_next >= NUM_TTY_CHANNELS)
priv->xmit_next = 0;
}
}
return 0;
}
/**
* mips_ejtag_fdc_handle() - Handle FDC events.
* @priv: Pointer to driver private data.
*
* Handle FDC events, such as new incoming data which needs draining out of the
* RX FIFO and feeding into the appropriate TTY ports, and space becoming
* available in the TX FIFO which would allow more data to be written out.
*/
static void mips_ejtag_fdc_handle(struct mips_ejtag_fdc_tty *priv)
{
struct mips_ejtag_fdc_tty_port *dport;
unsigned int stat, channel, data, cfg, i, flipped;
int len;
char buf[4];
for (;;) {
/* Find which channel the next FDC word is destined for */
stat = mips_ejtag_fdc_read(priv, REG_FDSTAT);
if (stat & REG_FDSTAT_RXE)
break;
channel = (stat & REG_FDSTAT_RXCHAN) >> REG_FDSTAT_RXCHAN_SHIFT;
dport = &priv->ports[channel];
/* Read out the FDC word, decode it, and pass to tty layer */
raw_spin_lock(&dport->rx_lock);
data = mips_ejtag_fdc_read(priv, REG_FDRX);
len = mips_ejtag_fdc_decode(data, buf);
dev_dbg(priv->dev, "%s%u: in %08x: \"%*pE\"\n",
priv->driver_name, channel, data, len, buf);
flipped = 0;
for (i = 0; i < len; ++i) {
#ifdef CONFIG_MAGIC_SYSRQ
#ifdef CONFIG_MIPS_EJTAG_FDC_KGDB
/* Support just Ctrl+C with KGDB channel */
if (channel == CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN) {
if (buf[i] == '\x03') { /* ^C */
handle_sysrq('g');
continue;
}
}
#endif
/* Support Ctrl+O for console channel */
if (channel == mips_ejtag_fdc_con.cons.index) {
if (buf[i] == '\x0f') { /* ^O */
priv->sysrq_pressed =
!priv->sysrq_pressed;
if (priv->sysrq_pressed)
continue;
} else if (priv->sysrq_pressed) {
handle_sysrq(buf[i]);
priv->sysrq_pressed = false;
continue;
}
}
#endif /* CONFIG_MAGIC_SYSRQ */
/* Check the port isn't being shut down */
if (!dport->rx_buf)
continue;
flipped += tty_insert_flip_char(&dport->port, buf[i],
TTY_NORMAL);
}
if (flipped)
tty_flip_buffer_push(&dport->port);
raw_spin_unlock(&dport->rx_lock);
}
/* If TX FIFO no longer full we may be able to write more data */
raw_spin_lock(&priv->lock);
if (priv->xmit_full && !(stat & REG_FDSTAT_TXF)) {
priv->xmit_full = false;
/* Disable TX interrupt */
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
cfg &= ~REG_FDCFG_TXINTTHRES;
cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
/* Wait the kthread so it can try writing more data */
wake_up_interruptible(&priv->waitqueue);
}
raw_spin_unlock(&priv->lock);
}
/**
* mips_ejtag_fdc_isr() - Interrupt handler.
* @irq: IRQ number.
* @dev_id: Pointer to driver private data.
*
* This is the interrupt handler, used when interrupts are enabled.
*
* It simply triggers the common FDC handler code.
*
* Returns: IRQ_HANDLED if an FDC interrupt was pending.
* IRQ_NONE otherwise.
*/
static irqreturn_t mips_ejtag_fdc_isr(int irq, void *dev_id)
{
struct mips_ejtag_fdc_tty *priv = dev_id;
/*
* We're not using proper per-cpu IRQs, so we must be careful not to
* handle IRQs on CPUs we're not interested in.
*
* Ideally proper per-cpu IRQ handlers could be used, but that doesn't
* fit well with the whole sharing of the main CPU IRQ lines. When we
* have something with a GIC that routes the FDC IRQs (i.e. no sharing
* between handlers) then support could be added more easily.
*/
if (smp_processor_id() != priv->cpu)
return IRQ_NONE;
/* If no FDC interrupt pending, it wasn't for us */
if (!(read_c0_cause() & CAUSEF_FDCI))
return IRQ_NONE;
mips_ejtag_fdc_handle(priv);
return IRQ_HANDLED;
}
/**
* mips_ejtag_fdc_tty_timer() - Poll FDC for incoming data.
* @opaque: Pointer to driver private data.
*
* This is the timer handler for when interrupts are disabled and polling the
* FDC state is required.
*
* It simply triggers the common FDC handler code and arranges for further
* polling.
*/
static void mips_ejtag_fdc_tty_timer(struct timer_list *t)
{
struct mips_ejtag_fdc_tty *priv = from_timer(priv, t, poll_timer);
mips_ejtag_fdc_handle(priv);
if (!priv->removing)
mod_timer(&priv->poll_timer, jiffies + FDC_TTY_POLL);
}
/* TTY Port operations */
static int mips_ejtag_fdc_tty_port_activate(struct tty_port *port,
struct tty_struct *tty)
{
struct mips_ejtag_fdc_tty_port *dport =
container_of(port, struct mips_ejtag_fdc_tty_port, port);
void *rx_buf;
/* Allocate the buffer we use for writing data */
if (tty_port_alloc_xmit_buf(port) < 0)
goto err;
/* Allocate the buffer we use for reading data */
rx_buf = kzalloc(RX_BUF_SIZE, GFP_KERNEL);
if (!rx_buf)
goto err_free_xmit;
raw_spin_lock_irq(&dport->rx_lock);
dport->rx_buf = rx_buf;
raw_spin_unlock_irq(&dport->rx_lock);
return 0;
err_free_xmit:
tty_port_free_xmit_buf(port);
err:
return -ENOMEM;
}
static void mips_ejtag_fdc_tty_port_shutdown(struct tty_port *port)
{
struct mips_ejtag_fdc_tty_port *dport =
container_of(port, struct mips_ejtag_fdc_tty_port, port);
struct mips_ejtag_fdc_tty *priv = dport->driver;
void *rx_buf;
unsigned int count;
spin_lock(&dport->xmit_lock);
count = dport->xmit_cnt;
spin_unlock(&dport->xmit_lock);
if (count) {
/*
* There's still data to write out, so wake and wait for the
* writer thread to drain the buffer.
*/
wake_up_interruptible(&priv->waitqueue);
wait_for_completion(&dport->xmit_empty);
}
/* Null the read buffer (timer could still be running!) */
raw_spin_lock_irq(&dport->rx_lock);
rx_buf = dport->rx_buf;
dport->rx_buf = NULL;
raw_spin_unlock_irq(&dport->rx_lock);
/* Free the read buffer */
kfree(rx_buf);
/* Free the write buffer */
tty_port_free_xmit_buf(port);
}
static const struct tty_port_operations mips_ejtag_fdc_tty_port_ops = {
.activate = mips_ejtag_fdc_tty_port_activate,
.shutdown = mips_ejtag_fdc_tty_port_shutdown,
};
/* TTY operations */
static int mips_ejtag_fdc_tty_install(struct tty_driver *driver,
struct tty_struct *tty)
{
struct mips_ejtag_fdc_tty *priv = driver->driver_state;
tty->driver_data = &priv->ports[tty->index];
return tty_port_install(&priv->ports[tty->index].port, driver, tty);
}
static int mips_ejtag_fdc_tty_open(struct tty_struct *tty, struct file *filp)
{
return tty_port_open(tty->port, tty, filp);
}
static void mips_ejtag_fdc_tty_close(struct tty_struct *tty, struct file *filp)
{
return tty_port_close(tty->port, tty, filp);
}
static void mips_ejtag_fdc_tty_hangup(struct tty_struct *tty)
{
struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
struct mips_ejtag_fdc_tty *priv = dport->driver;
/* Drop any data in the xmit buffer */
spin_lock(&dport->xmit_lock);
if (dport->xmit_cnt) {
atomic_sub(dport->xmit_cnt, &priv->xmit_total);
dport->xmit_cnt = 0;
dport->xmit_head = 0;
dport->xmit_tail = 0;
complete(&dport->xmit_empty);
}
spin_unlock(&dport->xmit_lock);
tty_port_hangup(tty->port);
}
static ssize_t mips_ejtag_fdc_tty_write(struct tty_struct *tty, const u8 *buf,
size_t total)
{
int count, block;
struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
struct mips_ejtag_fdc_tty *priv = dport->driver;
/*
* Write to output buffer.
*
* The reason that we asynchronously write the buffer is because if we
* were to write the buffer synchronously then because the channels are
* per-CPU the buffer would be written to the channel of whatever CPU
* we're running on.
*
* What we actually want to happen is have all input and output done on
* one CPU.
*/
spin_lock(&dport->xmit_lock);
/* Work out how many bytes we can write to the xmit buffer */
total = min_t(size_t, total, priv->xmit_size - dport->xmit_cnt);
atomic_add(total, &priv->xmit_total);
dport->xmit_cnt += total;
/* Write the actual bytes (may need splitting if it wraps) */
for (count = total; count; count -= block) {
block = min(count, (int)(priv->xmit_size - dport->xmit_head));
memcpy(dport->port.xmit_buf + dport->xmit_head, buf, block);
dport->xmit_head += block;
if (dport->xmit_head >= priv->xmit_size)
dport->xmit_head -= priv->xmit_size;
buf += block;
}
count = dport->xmit_cnt;
/* Xmit buffer no longer empty? */
if (count)
reinit_completion(&dport->xmit_empty);
spin_unlock(&dport->xmit_lock);
/* Wake up the kthread */
if (total)
wake_up_interruptible(&priv->waitqueue);
return total;
}
static unsigned int mips_ejtag_fdc_tty_write_room(struct tty_struct *tty)
{
struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
struct mips_ejtag_fdc_tty *priv = dport->driver;
unsigned int room;
/* Report the space in the xmit buffer */
spin_lock(&dport->xmit_lock);
room = priv->xmit_size - dport->xmit_cnt;
spin_unlock(&dport->xmit_lock);
return room;
}
static unsigned int mips_ejtag_fdc_tty_chars_in_buffer(struct tty_struct *tty)
{
struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
unsigned int chars;
/* Report the number of bytes in the xmit buffer */
spin_lock(&dport->xmit_lock);
chars = dport->xmit_cnt;
spin_unlock(&dport->xmit_lock);
return chars;
}
static const struct tty_operations mips_ejtag_fdc_tty_ops = {
.install = mips_ejtag_fdc_tty_install,
.open = mips_ejtag_fdc_tty_open,
.close = mips_ejtag_fdc_tty_close,
.hangup = mips_ejtag_fdc_tty_hangup,
.write = mips_ejtag_fdc_tty_write,
.write_room = mips_ejtag_fdc_tty_write_room,
.chars_in_buffer = mips_ejtag_fdc_tty_chars_in_buffer,
};
int __weak get_c0_fdc_int(void)
{
return -1;
}
static int mips_ejtag_fdc_tty_probe(struct mips_cdmm_device *dev)
{
int ret, nport;
struct mips_ejtag_fdc_tty_port *dport;
struct mips_ejtag_fdc_tty *priv;
struct tty_driver *driver;
unsigned int cfg, tx_fifo;
priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->cpu = dev->cpu;
priv->dev = &dev->dev;
mips_cdmm_set_drvdata(dev, priv);
atomic_set(&priv->xmit_total, 0);
raw_spin_lock_init(&priv->lock);
priv->reg = devm_ioremap(priv->dev, dev->res.start,
resource_size(&dev->res));
if (!priv->reg) {
dev_err(priv->dev, "ioremap failed for resource %pR\n",
&dev->res);
return -ENOMEM;
}
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
tx_fifo = (cfg & REG_FDCFG_TXFIFOSIZE) >> REG_FDCFG_TXFIFOSIZE_SHIFT;
/* Disable interrupts */
cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
/* Make each port's xmit FIFO big enough to fill FDC TX FIFO */
priv->xmit_size = min(tx_fifo * 4, (unsigned int)UART_XMIT_SIZE);
driver = tty_alloc_driver(NUM_TTY_CHANNELS, TTY_DRIVER_REAL_RAW);
if (IS_ERR(driver))
return PTR_ERR(driver);
priv->driver = driver;
driver->driver_name = "ejtag_fdc";
snprintf(priv->fdc_name, sizeof(priv->fdc_name), "ttyFDC%u", dev->cpu);
snprintf(priv->driver_name, sizeof(priv->driver_name), "%sc",
priv->fdc_name);
driver->name = priv->driver_name;
driver->major = 0; /* Auto-allocate */
driver->minor_start = 0;
driver->type = TTY_DRIVER_TYPE_SERIAL;
driver->subtype = SERIAL_TYPE_NORMAL;
driver->init_termios = tty_std_termios;
driver->init_termios.c_cflag |= CLOCAL;
driver->driver_state = priv;
tty_set_operations(driver, &mips_ejtag_fdc_tty_ops);
for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
dport = &priv->ports[nport];
dport->driver = priv;
tty_port_init(&dport->port);
dport->port.ops = &mips_ejtag_fdc_tty_port_ops;
raw_spin_lock_init(&dport->rx_lock);
spin_lock_init(&dport->xmit_lock);
/* The xmit buffer starts empty, i.e. completely written */
init_completion(&dport->xmit_empty);
complete(&dport->xmit_empty);
}
/* Set up the console */
mips_ejtag_fdc_con.regs[dev->cpu] = priv->reg;
if (dev->cpu == 0)
mips_ejtag_fdc_con.tty_drv = driver;
init_waitqueue_head(&priv->waitqueue);
/*
* Bind the writer thread to the right CPU so it can't migrate.
* The channels are per-CPU and we want all channel I/O to be on a
* single predictable CPU.
*/
priv->thread = kthread_run_on_cpu(mips_ejtag_fdc_put, priv,
dev->cpu, "ttyFDC/%u");
if (IS_ERR(priv->thread)) {
ret = PTR_ERR(priv->thread);
dev_err(priv->dev, "Couldn't create kthread (%d)\n", ret);
goto err_destroy_ports;
}
/* Look for an FDC IRQ */
priv->irq = get_c0_fdc_int();
/* Try requesting the IRQ */
if (priv->irq >= 0) {
/*
* IRQF_SHARED, IRQF_COND_SUSPEND: The FDC IRQ may be shared with
* other local interrupts such as the timer which sets
* IRQF_TIMER (including IRQF_NO_SUSPEND).
*
* IRQF_NO_THREAD: The FDC IRQ isn't individually maskable so it
* cannot be deferred and handled by a thread on RT kernels. For
* this reason any spinlocks used from the ISR are raw.
*/
ret = devm_request_irq(priv->dev, priv->irq, mips_ejtag_fdc_isr,
IRQF_PERCPU | IRQF_SHARED |
IRQF_NO_THREAD | IRQF_COND_SUSPEND,
priv->fdc_name, priv);
if (ret)
priv->irq = -1;
}
if (priv->irq >= 0) {
/* IRQ is usable, enable RX interrupt */
raw_spin_lock_irq(&priv->lock);
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
cfg &= ~REG_FDCFG_RXINTTHRES;
cfg |= REG_FDCFG_RXINTTHRES_NOTEMPTY;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
raw_spin_unlock_irq(&priv->lock);
} else {
/* If we didn't get an usable IRQ, poll instead */
timer_setup(&priv->poll_timer, mips_ejtag_fdc_tty_timer,
TIMER_PINNED);
priv->poll_timer.expires = jiffies + FDC_TTY_POLL;
/*
* Always attach the timer to the right CPU. The channels are
* per-CPU so all polling should be from a single CPU.
*/
add_timer_on(&priv->poll_timer, dev->cpu);
dev_info(priv->dev, "No usable IRQ, polling enabled\n");
}
ret = tty_register_driver(driver);
if (ret < 0) {
dev_err(priv->dev, "Couldn't install tty driver (%d)\n", ret);
goto err_stop_irq;
}
return 0;
err_stop_irq:
if (priv->irq >= 0) {
raw_spin_lock_irq(&priv->lock);
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
/* Disable interrupts */
cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
raw_spin_unlock_irq(&priv->lock);
} else {
priv->removing = true;
del_timer_sync(&priv->poll_timer);
}
kthread_stop(priv->thread);
err_destroy_ports:
if (dev->cpu == 0)
mips_ejtag_fdc_con.tty_drv = NULL;
for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
dport = &priv->ports[nport];
tty_port_destroy(&dport->port);
}
tty_driver_kref_put(priv->driver);
return ret;
}
static int mips_ejtag_fdc_tty_cpu_down(struct mips_cdmm_device *dev)
{
struct mips_ejtag_fdc_tty *priv = mips_cdmm_get_drvdata(dev);
unsigned int cfg;
if (priv->irq >= 0) {
raw_spin_lock_irq(&priv->lock);
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
/* Disable interrupts */
cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
raw_spin_unlock_irq(&priv->lock);
} else {
priv->removing = true;
del_timer_sync(&priv->poll_timer);
}
kthread_stop(priv->thread);
return 0;
}
static int mips_ejtag_fdc_tty_cpu_up(struct mips_cdmm_device *dev)
{
struct mips_ejtag_fdc_tty *priv = mips_cdmm_get_drvdata(dev);
unsigned int cfg;
int ret = 0;
if (priv->irq >= 0) {
/*
* IRQ is usable, enable RX interrupt
* This must be before kthread is restarted, as kthread may
* enable TX interrupt.
*/
raw_spin_lock_irq(&priv->lock);
cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
cfg |= REG_FDCFG_RXINTTHRES_NOTEMPTY;
mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
raw_spin_unlock_irq(&priv->lock);
} else {
/* Restart poll timer */
priv->removing = false;
add_timer_on(&priv->poll_timer, dev->cpu);
}
/* Restart the kthread */
/* Bind it back to the right CPU and set it off */
priv->thread = kthread_run_on_cpu(mips_ejtag_fdc_put, priv,
dev->cpu, "ttyFDC/%u");
if (IS_ERR(priv->thread)) {
ret = PTR_ERR(priv->thread);
dev_err(priv->dev, "Couldn't re-create kthread (%d)\n", ret);
goto out;
}
out:
return ret;
}
static const struct mips_cdmm_device_id mips_ejtag_fdc_tty_ids[] = {
{ .type = 0xfd },
{ }
};
static struct mips_cdmm_driver mips_ejtag_fdc_tty_driver = {
.drv = {
.name = "mips_ejtag_fdc",
},
.probe = mips_ejtag_fdc_tty_probe,
.cpu_down = mips_ejtag_fdc_tty_cpu_down,
.cpu_up = mips_ejtag_fdc_tty_cpu_up,
.id_table = mips_ejtag_fdc_tty_ids,
};
builtin_mips_cdmm_driver(mips_ejtag_fdc_tty_driver);
static int __init mips_ejtag_fdc_init_console(void)
{
return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_con);
}
console_initcall(mips_ejtag_fdc_init_console);
#ifdef CONFIG_MIPS_EJTAG_FDC_EARLYCON
static struct mips_ejtag_fdc_console mips_ejtag_fdc_earlycon = {
.cons = {
.name = "early_fdc",
.write = mips_ejtag_fdc_console_write,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = CONSOLE_CHANNEL,
},
.lock = __RAW_SPIN_LOCK_UNLOCKED(mips_ejtag_fdc_earlycon.lock),
};
int __init setup_early_fdc_console(void)
{
return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_earlycon);
}
#endif
#ifdef CONFIG_MIPS_EJTAG_FDC_KGDB
/* read buffer to allow decompaction */
static unsigned int kgdbfdc_rbuflen;
static unsigned int kgdbfdc_rpos;
static char kgdbfdc_rbuf[4];
/* write buffer to allow compaction */
static unsigned int kgdbfdc_wbuflen;
static char kgdbfdc_wbuf[4];
static void __iomem *kgdbfdc_setup(void)
{
void __iomem *regs;
unsigned int cpu;
/* Find address, piggy backing off console percpu regs */
cpu = smp_processor_id();
regs = mips_ejtag_fdc_con.regs[cpu];
/* First console output on this CPU? */
if (!regs) {
regs = mips_cdmm_early_probe(0xfd);
mips_ejtag_fdc_con.regs[cpu] = regs;
}
/* Already tried and failed to find FDC on this CPU? */
if (IS_ERR(regs))
return regs;
return regs;
}
/* read a character from the read buffer, filling from FDC RX FIFO */
static int kgdbfdc_read_char(void)
{
unsigned int stat, channel, data;
void __iomem *regs;
/* No more data, try and read another FDC word from RX FIFO */
if (kgdbfdc_rpos >= kgdbfdc_rbuflen) {
kgdbfdc_rpos = 0;
kgdbfdc_rbuflen = 0;
regs = kgdbfdc_setup();
if (IS_ERR(regs))
return NO_POLL_CHAR;
/* Read next word from KGDB channel */
do {
stat = __raw_readl(regs + REG_FDSTAT);
/* No data waiting? */
if (stat & REG_FDSTAT_RXE)
return NO_POLL_CHAR;
/* Read next word */
channel = (stat & REG_FDSTAT_RXCHAN) >>
REG_FDSTAT_RXCHAN_SHIFT;
data = __raw_readl(regs + REG_FDRX);
} while (channel != CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN);
/* Decode into rbuf */
kgdbfdc_rbuflen = mips_ejtag_fdc_decode(data, kgdbfdc_rbuf);
}
pr_devel("kgdbfdc r %c\n", kgdbfdc_rbuf[kgdbfdc_rpos]);
return kgdbfdc_rbuf[kgdbfdc_rpos++];
}
/* push an FDC word from write buffer to TX FIFO */
static void kgdbfdc_push_one(void)
{
const char *bufs[1] = { kgdbfdc_wbuf };
struct fdc_word word;
void __iomem *regs;
unsigned int i;
/* Construct a word from any data in buffer */
word = mips_ejtag_fdc_encode(bufs, &kgdbfdc_wbuflen, 1);
/* Relocate any remaining data to beginning of buffer */
kgdbfdc_wbuflen -= word.bytes;
for (i = 0; i < kgdbfdc_wbuflen; ++i)
kgdbfdc_wbuf[i] = kgdbfdc_wbuf[i + word.bytes];
regs = kgdbfdc_setup();
if (IS_ERR(regs))
return;
/* Busy wait until there's space in fifo */
while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
;
__raw_writel(word.word,
regs + REG_FDTX(CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN));
}
/* flush the whole write buffer to the TX FIFO */
static void kgdbfdc_flush(void)
{
while (kgdbfdc_wbuflen)
kgdbfdc_push_one();
}
/* write a character into the write buffer, writing out if full */
static void kgdbfdc_write_char(u8 chr)
{
pr_devel("kgdbfdc w %c\n", chr);
kgdbfdc_wbuf[kgdbfdc_wbuflen++] = chr;
if (kgdbfdc_wbuflen >= sizeof(kgdbfdc_wbuf))
kgdbfdc_push_one();
}
static struct kgdb_io kgdbfdc_io_ops = {
.name = "kgdbfdc",
.read_char = kgdbfdc_read_char,
.write_char = kgdbfdc_write_char,
.flush = kgdbfdc_flush,
};
static int __init kgdbfdc_init(void)
{
kgdb_register_io_module(&kgdbfdc_io_ops);
return 0;
}
early_initcall(kgdbfdc_init);
#endif