tty: bfin_jtag_comm: emulate a TTY over the Blackfin EMUDAT/JTAG interface (0b914218) · Commits · e / devices / android_kernel_fairphone_FP3

drivers/char/Kconfig

+13 −0

Original line number	Diff line number	Diff line
		@@ -97,6 +97,19 @@ config DEVKMEM
		kind of kernel debugging operations.
		When in doubt, say "N".

		config BFIN_JTAG_COMM
		tristate "Blackfin JTAG Communication"
		depends on BLACKFIN
		help
		Add support for emulating a TTY device over the Blackfin JTAG.

		To compile this driver as a module, choose M here: the
		module will be called bfin_jtag_comm.

		config BFIN_JTAG_COMM_CONSOLE
		bool "Console on Blackfin JTAG"
		depends on BFIN_JTAG_COMM=y

		config SERIAL_NONSTANDARD
		bool "Non-standard serial port support"
		depends on HAS_IOMEM

drivers/char/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@ obj-$(CONFIG_LEGACY_PTYS) += pty.o
		obj-$(CONFIG_UNIX98_PTYS) += pty.o
		obj-y += misc.o
		obj-$(CONFIG_VT) += vt_ioctl.o vc_screen.o selection.o keyboard.o
		obj-$(CONFIG_BFIN_JTAG_COMM) += bfin_jtag_comm.o
		obj-$(CONFIG_CONSOLE_TRANSLATIONS) += consolemap.o consolemap_deftbl.o
		obj-$(CONFIG_HW_CONSOLE) += vt.o defkeymap.o
		obj-$(CONFIG_AUDIT) += tty_audit.o

drivers/char/bfin_jtag_comm.c

0 → 100644

+365 −0

Original line number	Diff line number	Diff line
		/*
		* TTY over Blackfin JTAG Communication
		*
		* Copyright 2008-2009 Analog Devices Inc.
		*
		* Enter bugs at http://blackfin.uclinux.org/
		*
		* Licensed under the GPL-2 or later.
		*/

		#include <linux/circ_buf.h>
		#include <linux/console.h>
		#include <linux/delay.h>
		#include <linux/err.h>
		#include <linux/kernel.h>
		#include <linux/kthread.h>
		#include <linux/module.h>
		#include <linux/mutex.h>
		#include <linux/sched.h>
		#include <linux/tty.h>
		#include <linux/tty_driver.h>
		#include <linux/tty_flip.h>
		#include <asm/atomic.h>

		/* See the Debug/Emulation chapter in the HRM */
		#define EMUDOF 0x00000001 /* EMUDAT_OUT full & valid */
		#define EMUDIF 0x00000002 /* EMUDAT_IN full & valid */
		#define EMUDOOVF 0x00000004 /* EMUDAT_OUT overflow */
		#define EMUDIOVF 0x00000008 /* EMUDAT_IN overflow */

		#define DRV_NAME "bfin-jtag-comm"
		#define DEV_NAME "ttyBFJC"

		#define pr_init(fmt, args...) ({ static const __initdata char __fmt[] = fmt; printk(__fmt, ## args); })
		#define debug(fmt, args...) pr_debug(DRV_NAME ": " fmt, ## args)

		static inline uint32_t bfin_write_emudat(uint32_t emudat)
		{
		__asm__ __volatile__("emudat = %0;" : : "d"(emudat));
		return emudat;
		}

		static inline uint32_t bfin_read_emudat(void)
		{
		uint32_t emudat;
		__asm__ __volatile__("%0 = emudat;" : "=d"(emudat));
		return emudat;
		}

		static inline uint32_t bfin_write_emudat_chars(char a, char b, char c, char d)
		{
		return bfin_write_emudat((a << 0) \| (b << 8) \| (c << 16) \| (d << 24));
		}

		#define CIRC_SIZE 2048 /* see comment in tty_io.c:do_tty_write() */
		#define CIRC_MASK (CIRC_SIZE - 1)
		#define circ_empty(circ) ((circ)->head == (circ)->tail)
		#define circ_free(circ) CIRC_SPACE((circ)->head, (circ)->tail, CIRC_SIZE)
		#define circ_cnt(circ) CIRC_CNT((circ)->head, (circ)->tail, CIRC_SIZE)
		#define circ_byte(circ, idx) ((circ)->buf[(idx) & CIRC_MASK])

		static struct tty_driver *bfin_jc_driver;
		static struct task_struct *bfin_jc_kthread;
		static struct tty_struct * volatile bfin_jc_tty;
		static unsigned long bfin_jc_count;
		static DEFINE_MUTEX(bfin_jc_tty_mutex);
		static volatile struct circ_buf bfin_jc_write_buf;

		static int
		bfin_jc_emudat_manager(void *arg)
		{
		uint32_t inbound_len = 0, outbound_len = 0;

		while (!kthread_should_stop()) {
		/* no one left to give data to, so sleep */
		if (bfin_jc_tty == NULL && circ_empty(&bfin_jc_write_buf)) {
		debug("waiting for readers\n");
		__set_current_state(TASK_UNINTERRUPTIBLE);
		schedule();
		__set_current_state(TASK_RUNNING);
		}

		/* no data available, so just chill */
		if (!(bfin_read_DBGSTAT() & EMUDIF) && circ_empty(&bfin_jc_write_buf)) {
		debug("waiting for data (in_len = %i) (circ: %i %i)\n",
		inbound_len, bfin_jc_write_buf.tail, bfin_jc_write_buf.head);
		if (inbound_len)
		schedule();
		else
		schedule_timeout_interruptible(HZ);
		continue;
		}

		/* if incoming data is ready, eat it */
		if (bfin_read_DBGSTAT() & EMUDIF) {
		struct tty_struct *tty;
		mutex_lock(&bfin_jc_tty_mutex);
		tty = (struct tty_struct *)bfin_jc_tty;
		if (tty != NULL) {
		uint32_t emudat = bfin_read_emudat();
		if (inbound_len == 0) {
		debug("incoming length: 0x%08x\n", emudat);
		inbound_len = emudat;
		} else {
		size_t num_chars = (4 <= inbound_len ? 4 : inbound_len);
		debug(" incoming data: 0x%08x (pushing %zu)\n", emudat, num_chars);
		inbound_len -= num_chars;
		tty_insert_flip_string(tty, (unsigned char *)&emudat, num_chars);
		tty_flip_buffer_push(tty);
		}
		}
		mutex_unlock(&bfin_jc_tty_mutex);
		}

		/* if outgoing data is ready, post it */
		if (!(bfin_read_DBGSTAT() & EMUDOF) && !circ_empty(&bfin_jc_write_buf)) {
		if (outbound_len == 0) {
		outbound_len = circ_cnt(&bfin_jc_write_buf);
		bfin_write_emudat(outbound_len);
		debug("outgoing length: 0x%08x\n", outbound_len);
		} else {
		struct tty_struct *tty;
		int tail = bfin_jc_write_buf.tail;
		size_t ate = (4 <= outbound_len ? 4 : outbound_len);
		uint32_t emudat =
		bfin_write_emudat_chars(
		circ_byte(&bfin_jc_write_buf, tail + 0),
		circ_byte(&bfin_jc_write_buf, tail + 1),
		circ_byte(&bfin_jc_write_buf, tail + 2),
		circ_byte(&bfin_jc_write_buf, tail + 3)
		);
		bfin_jc_write_buf.tail += ate;
		outbound_len -= ate;
		mutex_lock(&bfin_jc_tty_mutex);
		tty = (struct tty_struct *)bfin_jc_tty;
		if (tty)
		tty_wakeup(tty);
		mutex_unlock(&bfin_jc_tty_mutex);
		debug(" outgoing data: 0x%08x (pushing %zu)\n", emudat, ate);
		}
		}
		}

		__set_current_state(TASK_RUNNING);
		return 0;
		}

		static int
		bfin_jc_open(struct tty_struct tty, struct file filp)
		{
		mutex_lock(&bfin_jc_tty_mutex);
		debug("open %lu\n", bfin_jc_count);
		++bfin_jc_count;
		bfin_jc_tty = tty;
		wake_up_process(bfin_jc_kthread);
		mutex_unlock(&bfin_jc_tty_mutex);
		return 0;
		}

		static void
		bfin_jc_close(struct tty_struct tty, struct file filp)
		{
		mutex_lock(&bfin_jc_tty_mutex);
		debug("close %lu\n", bfin_jc_count);
		if (--bfin_jc_count == 0)
		bfin_jc_tty = NULL;
		wake_up_process(bfin_jc_kthread);
		mutex_unlock(&bfin_jc_tty_mutex);
		}

		/* XXX: we dont handle the put_char() case where we must handle count = 1 */
		static int
		bfin_jc_circ_write(const unsigned char *buf, int count)
		{
		int i;
		count = min(count, circ_free(&bfin_jc_write_buf));
		debug("going to write chunk of %i bytes\n", count);
		for (i = 0; i < count; ++i)
		circ_byte(&bfin_jc_write_buf, bfin_jc_write_buf.head + i) = buf[i];
		bfin_jc_write_buf.head += i;
		return i;
		}

		#ifndef CONFIG_BFIN_JTAG_COMM_CONSOLE
		# define acquire_console_sem()
		# define release_console_sem()
		#endif
		static int
		bfin_jc_write(struct tty_struct tty, const unsigned char buf, int count)
		{
		int i;
		acquire_console_sem();
		i = bfin_jc_circ_write(buf, count);
		release_console_sem();
		wake_up_process(bfin_jc_kthread);
		return i;
		}

		static void
		bfin_jc_flush_chars(struct tty_struct *tty)
		{
		wake_up_process(bfin_jc_kthread);
		}

		static int
		bfin_jc_write_room(struct tty_struct *tty)
		{
		return circ_free(&bfin_jc_write_buf);
		}

		static int
		bfin_jc_chars_in_buffer(struct tty_struct *tty)
		{
		return circ_cnt(&bfin_jc_write_buf);
		}

		static void
		bfin_jc_wait_until_sent(struct tty_struct *tty, int timeout)
		{
		unsigned long expire = jiffies + timeout;
		while (!circ_empty(&bfin_jc_write_buf)) {
		if (signal_pending(current))
		break;
		if (time_after(jiffies, expire))
		break;
		}
		}

		static struct tty_operations bfin_jc_ops = {
		.open = bfin_jc_open,
		.close = bfin_jc_close,
		.write = bfin_jc_write,
		/.put_char = bfin_jc_put_char,/
		.flush_chars = bfin_jc_flush_chars,
		.write_room = bfin_jc_write_room,
		.chars_in_buffer = bfin_jc_chars_in_buffer,
		.wait_until_sent = bfin_jc_wait_until_sent,
		};

		static int __init bfin_jc_init(void)
		{
		int ret;

		bfin_jc_kthread = kthread_create(bfin_jc_emudat_manager, NULL, DRV_NAME);
		if (IS_ERR(bfin_jc_kthread))
		return PTR_ERR(bfin_jc_kthread);

		ret = -ENOMEM;

		bfin_jc_write_buf.head = bfin_jc_write_buf.tail = 0;
		bfin_jc_write_buf.buf = kmalloc(CIRC_SIZE, GFP_KERNEL);
		if (!bfin_jc_write_buf.buf)
		goto err;

		bfin_jc_driver = alloc_tty_driver(1);
		if (!bfin_jc_driver)
		goto err;

		bfin_jc_driver->owner = THIS_MODULE;
		bfin_jc_driver->driver_name = DRV_NAME;
		bfin_jc_driver->name = DEV_NAME;
		bfin_jc_driver->type = TTY_DRIVER_TYPE_SERIAL;
		bfin_jc_driver->subtype = SERIAL_TYPE_NORMAL;
		bfin_jc_driver->init_termios = tty_std_termios;
		tty_set_operations(bfin_jc_driver, &bfin_jc_ops);

		ret = tty_register_driver(bfin_jc_driver);
		if (ret)
		goto err;

		pr_init(KERN_INFO DRV_NAME ": initialized\n");

		return 0;

		err:
		put_tty_driver(bfin_jc_driver);
		kfree(bfin_jc_write_buf.buf);
		kthread_stop(bfin_jc_kthread);
		return ret;
		}
		module_init(bfin_jc_init);

		static void __exit bfin_jc_exit(void)
		{
		kthread_stop(bfin_jc_kthread);
		kfree(bfin_jc_write_buf.buf);
		tty_unregister_driver(bfin_jc_driver);
		put_tty_driver(bfin_jc_driver);
		}
		module_exit(bfin_jc_exit);

		#if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) \|\| defined(CONFIG_EARLY_PRINTK)
		static void
		bfin_jc_straight_buffer_write(const char *buf, unsigned count)
		{
		unsigned ate = 0;
		while (bfin_read_DBGSTAT() & EMUDOF)
		continue;
		bfin_write_emudat(count);
		while (ate < count) {
		while (bfin_read_DBGSTAT() & EMUDOF)
		continue;
		bfin_write_emudat_chars(buf[ate], buf[ate+1], buf[ate+2], buf[ate+3]);
		ate += 4;
		}
		}
		#endif

		#ifdef CONFIG_BFIN_JTAG_COMM_CONSOLE
		static void
		bfin_jc_console_write(struct console co, const char buf, unsigned count)
		{
		if (bfin_jc_kthread == NULL)
		bfin_jc_straight_buffer_write(buf, count);
		else
		bfin_jc_circ_write(buf, count);
		}

		static struct tty_driver *
		bfin_jc_console_device(struct console co, int index)
		{
		*index = co->index;
		return bfin_jc_driver;
		}

		static struct console bfin_jc_console = {
		.name = DEV_NAME,
		.write = bfin_jc_console_write,
		.device = bfin_jc_console_device,
		.flags = CON_ANYTIME \| CON_PRINTBUFFER,
		.index = -1,
		};

		static int __init bfin_jc_console_init(void)
		{
		register_console(&bfin_jc_console);
		return 0;
		}
		console_initcall(bfin_jc_console_init);
		#endif

		#ifdef CONFIG_EARLY_PRINTK
		static void __init
		bfin_jc_early_write(struct console co, const char buf, unsigned int count)
		{
		bfin_jc_straight_buffer_write(buf, count);
		}

		static struct __initdata console bfin_jc_early_console = {
		.name = "early_BFJC",
		.write = bfin_jc_early_write,
		.flags = CON_ANYTIME \| CON_PRINTBUFFER,
		.index = -1,
		};

		struct console * __init
		bfin_jc_early_init(unsigned int port, unsigned int cflag)
		{
		return &bfin_jc_early_console;
		}
		#endif

		MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
		MODULE_DESCRIPTION("TTY over Blackfin JTAG Communication");
		MODULE_LICENSE("GPL");