--- /dev/null
+/*
+ * TTY driver for MIPS EJTAG Fast Debug Channels.
+ *
+ * Copyright (C) 2007-2015 Imagination Technologies Ltd
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of this archive for more
+ * details.
+ */
+
+#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/kthread.h>
+#include <linux/sched.h>
+#include <linux/serial.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 */
+
+#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.
+ */
+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;
+};
+
+/* Hardware access */
+
+static inline void mips_ejtag_fdc_write(struct mips_ejtag_fdc_tty *priv,
+ unsigned int offs, unsigned int data)
+{
+ iowrite32(data, priv->reg + offs);
+}
+
+static inline unsigned int mips_ejtag_fdc_read(struct mips_ejtag_fdc_tty *priv,
+ unsigned int offs)
+{
+ return ioread32(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;
+ 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 (ioread32(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
+ ;
+ iowrite32(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);
+
+ /* Check the port isn't being shut down */
+ if (!dport->rx_buf)
+ goto unlock;
+
+ 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)
+ flipped += tty_insert_flip_char(&dport->port, buf[i],
+ TTY_NORMAL);
+ if (flipped)
+ tty_flip_buffer_push(&dport->port);
+unlock:
+ 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(unsigned long opaque)
+{
+ struct mips_ejtag_fdc_tty *priv = (void *)opaque;
+
+ mips_ejtag_fdc_handle(priv);
+ if (!priv->removing)
+ mod_timer_pinned(&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 int mips_ejtag_fdc_tty_write(struct tty_struct *tty,
+ const unsigned char *buf, int 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(total, (int)(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 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;
+ 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 int mips_ejtag_fdc_tty_chars_in_buffer(struct tty_struct *tty)
+{
+ struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
+ 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,
+};
+
+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_nocache(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)SERIAL_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);
+ priv->thread = kthread_create(mips_ejtag_fdc_put, priv, priv->fdc_name);
+ 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;
+ }
+ /*
+ * 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.
+ */
+ kthread_bind(priv->thread, dev->cpu);
+ wake_up_process(priv->thread);
+
+ /* Look for an FDC IRQ */
+ priv->irq = -1;
+ if (get_c0_fdc_int)
+ priv->irq = get_c0_fdc_int();
+
+ /* Try requesting the IRQ */
+ if (priv->irq >= 0) {
+ /*
+ * IRQF_SHARED, IRQF_NO_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_NO_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 */
+ setup_timer(&priv->poll_timer, mips_ejtag_fdc_tty_timer,
+ (unsigned long)priv);
+ 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);
+ }
+ put_tty_driver(priv->driver);
+ return ret;
+}
+
+static int mips_ejtag_fdc_tty_remove(struct mips_cdmm_device *dev)
+{
+ struct mips_ejtag_fdc_tty *priv = mips_cdmm_get_drvdata(dev);
+ struct mips_ejtag_fdc_tty_port *dport;
+ int nport;
+ 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);
+ if (dev->cpu == 0)
+ mips_ejtag_fdc_con.tty_drv = NULL;
+ tty_unregister_driver(priv->driver);
+ for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
+ dport = &priv->ports[nport];
+ tty_port_destroy(&dport->port);
+ }
+ put_tty_driver(priv->driver);
+ return 0;
+}
+
+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 */
+ priv->thread = kthread_create(mips_ejtag_fdc_put, priv, priv->fdc_name);
+ if (IS_ERR(priv->thread)) {
+ ret = PTR_ERR(priv->thread);
+ dev_err(priv->dev, "Couldn't re-create kthread (%d)\n", ret);
+ goto out;
+ }
+ /* Bind it back to the right CPU and set it off */
+ kthread_bind(priv->thread, dev->cpu);
+ wake_up_process(priv->thread);
+out:
+ return ret;
+}
+
+static 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,
+ .remove = mips_ejtag_fdc_tty_remove,
+ .cpu_down = mips_ejtag_fdc_tty_cpu_down,
+ .cpu_up = mips_ejtag_fdc_tty_cpu_up,
+ .id_table = mips_ejtag_fdc_tty_ids,
+};
+module_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);
projects / linux-drm-fsl-dcu.git / commitdiff