[PATCH v2 43/44] tty/metag_da: Add metag DA TTY driver

From: James Hogan
Date: Wed Dec 05 2012 - 11:09:47 EST

Add a TTY driver for communicating over a Meta DA (Debug Adapter)
channel using the bios channel SWITCH operation.

Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
MAINTAINERS | 1 +
arch/metag/Kconfig | 4 +-
arch/metag/configs/meta1_defconfig | 2 +
arch/metag/configs/meta2_defconfig | 2 +
arch/metag/configs/meta2_smp_defconfig | 2 +
arch/metag/kernel/setup.c | 12 +
drivers/tty/Kconfig | 13 +
drivers/tty/Makefile | 1 +
drivers/tty/metag_da.c | 523 ++++++++++++++++++++++++++++++++
9 files changed, 559 insertions(+), 1 deletions(-)
create mode 100644 drivers/tty/metag_da.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b2b64ea..9ed766d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4856,6 +4856,7 @@ S: Maintained
F: arch/metag/
F: Documentation/metag/
F: Documentation/devicetree/bindings/metag/
+F: drivers/tty/metag_da.c

MICROBLAZE ARCHITECTURE
M: Michal Simek <monstr@xxxxxxxxx>
diff --git a/arch/metag/Kconfig b/arch/metag/Kconfig
index 5807964..9489431 100644
--- a/arch/metag/Kconfig
+++ b/arch/metag/Kconfig
@@ -220,7 +220,9 @@ config METAG_DA
of the DA will be detected automatically at boot, so it is safe to say
Y to this option even when booting without a DA.

- This enables support for services provided by DA JTAG debug adapters.
+ This enables support for services provided by DA JTAG debug adapters,
+ such as:
+ - communication over DA channels (such as the console driver).

menu "Boot options"

diff --git a/arch/metag/configs/meta1_defconfig b/arch/metag/configs/meta1_defconfig
index 76a2d5f..f440e5a 100644
--- a/arch/metag/configs/meta1_defconfig
+++ b/arch/metag/configs/meta1_defconfig
@@ -28,6 +28,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
# CONFIG_SERIO is not set
# CONFIG_VT is not set
# CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
# CONFIG_DEVKMEM is not set
# CONFIG_HW_RANDOM is not set
# CONFIG_HWMON is not set
diff --git a/arch/metag/configs/meta2_defconfig b/arch/metag/configs/meta2_defconfig
index 0b46722..b9ecdd2 100644
--- a/arch/metag/configs/meta2_defconfig
+++ b/arch/metag/configs/meta2_defconfig
@@ -29,6 +29,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
# CONFIG_SERIO is not set
# CONFIG_VT is not set
# CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
# CONFIG_DEVKMEM is not set
# CONFIG_HW_RANDOM is not set
# CONFIG_HWMON is not set
diff --git a/arch/metag/configs/meta2_smp_defconfig b/arch/metag/configs/meta2_smp_defconfig
index b254e6c..87b60eb 100644
--- a/arch/metag/configs/meta2_smp_defconfig
+++ b/arch/metag/configs/meta2_smp_defconfig
@@ -30,6 +30,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
# CONFIG_SERIO is not set
# CONFIG_VT is not set
# CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
# CONFIG_DEVKMEM is not set
# CONFIG_HW_RANDOM is not set
# CONFIG_HWMON is not set
diff --git a/arch/metag/kernel/setup.c b/arch/metag/kernel/setup.c
index 65e8641..35d129f 100644
--- a/arch/metag/kernel/setup.c
+++ b/arch/metag/kernel/setup.c
@@ -61,6 +61,11 @@ extern char _heap_start[];
extern u32 __dtb_start[];
#endif

+#ifdef CONFIG_DA_CONSOLE
+/* Our early channel based console driver */
+extern struct console dash_console;
+#endif
+
struct machine_desc *machine_desc __initdata;

/*
@@ -184,6 +189,13 @@ void __init setup_arch(char **cmdline_p)
int heap_id, i;

metag_da_probe();
+#ifdef CONFIG_DA_CONSOLE
+ if (metag_da_enabled()) {
+ /* An early channel based console driver */
+ register_console(&dash_console);
+ add_preferred_console("ttyDA", 1, NULL);
+ }
+#endif

/* try interpreting the argument as a device tree */
machine_desc = setup_machine_fdt(original_cmd_line);
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index d8e05ee..182f92b 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -387,3 +387,16 @@ config PPC_EARLY_DEBUG_EHV_BC_HANDLE
If the number you specify is not a valid byte channel handle, then
there simply will be no early console output. This is true also
if you don't boot under a hypervisor at all.
+
+config DA_TTY
+ bool "DA TTY"
+ depends on METAG_DA
+ select SERIAL_NONSTANDARD
+ help
+ This enables a TTY on a Dash channel.
+
+config DA_CONSOLE
+ bool "DA Console"
+ depends on DA_TTY
+ help
+ This enables a console on a Dash channel.
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index 2953059..dbd7745 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -27,5 +27,6 @@ obj-$(CONFIG_SYNCLINK_GT) += synclink_gt.o
obj-$(CONFIG_SYNCLINKMP) += synclinkmp.o
obj-$(CONFIG_SYNCLINK) += synclink.o
obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
+obj-$(CONFIG_DA_TTY) += metag_da.o

obj-y += ipwireless/
diff --git a/drivers/tty/metag_da.c b/drivers/tty/metag_da.c
new file mode 100644
index 0000000..e46d80b
--- /dev/null
+++ b/drivers/tty/metag_da.c
@@ -0,0 +1,523 @@
+/*
+ * dashtty.c - tty driver for Dash channels interface.
+ *
+ * Copyright (C) 2007,2008,2012 Imagination Technologies
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/string.h>
+#include <linux/sched.h>
+#include <linux/console.h>
+#include <linux/uaccess.h>
+#include <linux/kthread.h>
+
+#include <asm/da.h>
+
+/* Channel error codes */
+#define CONAOK 0
+#define CONERR 1
+#define CONBAD 2
+#define CONPRM 3
+#define CONADR 4
+#define CONCNT 5
+#define CONCBF 6
+#define CONCBE 7
+#define CONBSY 8
+
+/* Default channel for the console */
+#define CONSOLE_CHANNEL 1
+
+/* First channel available for tty use. */
+#define FIRST_TTY_CHANNEL 0
+
+#define NUM_TTY_CHANNELS 6
+
+/* Auto allocate */
+#define DA_TTY_MAJOR 0
+
+/* A speedy poll rate helps the userland debug process connection response.
+ * But, if you set it too high then no other userland processes get much
+ * of a look in.
+ */
+#define DA_TTY_POLL (HZ / 50)
+
+static int num_channels_need_poll;
+
+static struct timer_list poll_timer;
+
+static struct tty_driver *channel_driver;
+
+static struct task_struct *dashtty_thread;
+
+#define RX_BUF_SIZE 1024
+
+enum {
+ INCHR = 1,
+ OUTCHR,
+ RDBUF,
+ WRBUF,
+ RDSTAT
+};
+
+/* One struct dashtty exists per open channel. */
+struct dashtty {
+ struct tty_struct *tty;
+ struct tty_port *port;
+};
+
+static struct tty_port dashtty_ports[NUM_TTY_CHANNELS];
+
+struct dashbuf {
+ struct list_head entry;
+ struct dashtty *tty;
+ unsigned char *buf;
+ int count;
+ int chan;
+};
+
+static struct dashtty *dashtty_ttys[NUM_TTY_CHANNELS];
+static struct list_head dashtty_output_queue;
+static spinlock_t dashtty_q_lock;
+static wait_queue_head_t dashtty_waitqueue;
+
+static DEFINE_MUTEX(dashtty_mutex);
+
+/*
+ * Low-level DA channel access routines
+ */
+static int chancall(int bios_function, int channel, int arg2, void *arg3,
+ void *arg4)
+{
+ register int bios_function__ __asm__("D1Ar1") = bios_function;
+ register int channel__ __asm__("D0Ar2") = channel;
+ register int arg2__ __asm__("D1Ar3") = arg2;
+ register void *arg3__ __asm__("D0Ar4") = arg3;
+ register void *arg4__ __asm__("D1Ar5") = arg4;
+ register int bios_call __asm__("D0Ar6") = 3;
+ register int result __asm__("D0Re0");
+
+ __asm__ volatile (
+ "SETL [A0StP++], %6,%5\n\t"
+ "SETL [A0StP++], %4,%3\n\t"
+ "SETL [A0StP++], %2,%1\n\t"
+ "ADD A0StP, A0StP, #8\n\t"
+ "SWITCH #0x0C30208\n\t"
+ "GETD %0, [A0StP+#-8]\n\t"
+ "SUB A0StP, A0StP, #(4*6)+8\n\t"
+ : "=r" (result)/* outs */
+ : "r" (bios_function__), "r" (channel__), "r" (arg2__),
+ "r" (arg3__), "r" (arg4__), "r" (bios_call) /* ins */
+ : "memory");
+
+ return result;
+}
+
+/*
+ * Attempts to fetch count bytes from channel channel and returns actual count.
+ */
+static int fetch_data(int channel)
+{
+ struct dashtty *dashtty = dashtty_ttys[channel];
+ struct tty_struct *tty = dashtty->tty;
+ int received = 0;
+
+ if (chancall(RDBUF, channel, RX_BUF_SIZE,
+ (void *)dashtty->port->xmit_buf, &received) == CONAOK) {
+ if (received) {
+ int space;
+ unsigned char *cbuf;
+
+ space = tty_prepare_flip_string(tty, &cbuf, received);
+
+ if (space <= 0)
+ return 0;
+
+ memcpy(cbuf, dashtty->port->xmit_buf, space);
+ tty_flip_buffer_push(tty);
+ }
+ }
+
+ return received;
+}
+
+/*
+ * Finds the next channel to poll
+ */
+static int find_channel_to_poll(void)
+{
+ static int last_polled_channel = FIRST_TTY_CHANNEL;
+
+ int this_channel = last_polled_channel;
+
+ while (++this_channel != last_polled_channel) {
+ if (this_channel >= NUM_TTY_CHANNELS)
+ this_channel = 0;
+
+ if (dashtty_ttys[this_channel]) {
+ last_polled_channel = this_channel;
+ break;
+ }
+ }
+ return last_polled_channel;
+}
+
+static int put_data(void *arg)
+{
+ struct dashbuf *dbuf;
+ int number_written;
+
+ __set_current_state(TASK_RUNNING);
+ while (!kthread_should_stop()) {
+ /*
+ * Pick up all the output buffers and write them out.
+ *
+ * FIXME: should we check with ASE how much room we have?
+ * Ideally, this will already have been done by write_room ??
+ */
+ spin_lock(&dashtty_q_lock);
+
+ while (!list_empty(&dashtty_output_queue)) {
+ dbuf = list_entry(dashtty_output_queue.next,
+ struct dashbuf, entry);
+
+ chancall(WRBUF, dbuf->chan, dbuf->count,
+ (void *)dbuf->buf, &number_written);
+
+ if (list_is_last(&dbuf->entry,
+ &dashtty_output_queue))
+ list_del_init(&dashtty_output_queue);
+ else
+ list_del(&dbuf->entry);
+
+ /*
+ * FIXME: should we only be doing wake when we
+ * know something is sleeping?
+ */
+ tty_wakeup(dbuf->tty->tty);
+
+ kfree(dbuf->buf);
+ kfree(dbuf);
+ }
+ spin_unlock(&dashtty_q_lock);
+
+ wait_event_interruptible(dashtty_waitqueue,
+ !list_empty(&dashtty_output_queue));
+ }
+
+ return 0;
+}
+
+/*
+ * This gets called every DA_TTY_POLL and polls the channels for data
+ */
+static void dashtty_timer(unsigned long ignored)
+{
+ struct dashtty *dtty;
+ int this_channel;
+
+ /* If there are no ports open do nothing and don't poll again. */
+ if (num_channels_need_poll == 0)
+ return;
+
+ this_channel = find_channel_to_poll();
+ dtty = dashtty_ttys[this_channel];
+
+ /* Did we find a channel to poll ? */
+ if (dtty)
+ fetch_data(this_channel);
+
+ mod_timer_pinned(&poll_timer, jiffies + DA_TTY_POLL);
+}
+
+static void add_poll_timer(struct timer_list *poll_timer)
+{
+ init_timer(poll_timer);
+
+ poll_timer->function = dashtty_timer;
+ poll_timer->expires = jiffies + DA_TTY_POLL;
+
+ /*
+ * Always attach the timer to the boot CPU.
+ */
+ add_timer_on(poll_timer, 0);
+}
+
+static int dashtty_open(struct tty_struct *tty, struct file *filp)
+{
+ struct dashtty *dashtty;
+ int line;
+
+ if (!tty)
+ return -ENODEV;
+
+ line = tty->index;
+
+ if (line < 0 || line >= NUM_TTY_CHANNELS)
+ return -ENODEV;
+
+ mutex_lock(&dashtty_mutex);
+ dashtty = dashtty_ttys[line];
+ if (!dashtty) {
+ dashtty = kzalloc(sizeof(struct dashtty), GFP_KERNEL);
+
+ if (!dashtty)
+ return -ENOMEM;
+
+ dashtty->port = &dashtty_ports[line];
+
+ dashtty->port->xmit_buf = kzalloc(RX_BUF_SIZE, GFP_KERNEL);
+ dashtty->tty = tty;
+ dashtty_ttys[line] = dashtty;
+ }
+
+ dashtty->port->count++;
+ tty_port_tty_set(dashtty->port, tty);
+
+ mutex_unlock(&dashtty_mutex);
+
+ /*
+ * Don't add the poll timer if we're opening a console. This
+ * avoids the overhead of polling the Dash but means it is not
+ * possible to have a login on /dev/console.
+ *
+ */
+ if (line == CONSOLE_CHANNEL)
+ return 0;
+
+ if (num_channels_need_poll == 0)
+ add_poll_timer(&poll_timer);
+
+ num_channels_need_poll++;
+
+ return 0;
+}
+
+static void dashtty_close(struct tty_struct *tty, struct file *filp)
+{
+ int line;
+
+ if (!tty)
+ return;
+
+ line = tty->index;
+
+ if (line < 0 || line >= NUM_TTY_CHANNELS)
+ return;
+
+ mutex_lock(&dashtty_mutex);
+ dashtty_ttys[line]->port->count--;
+
+ if (!dashtty_ttys[line]->port->count) {
+ tty_port_tty_set(dashtty_ttys[line]->port, NULL);
+ kfree(dashtty_ttys[line]->port->xmit_buf);
+ kfree(dashtty_ttys[line]);
+ dashtty_ttys[line] = NULL;
+ }
+
+ mutex_unlock(&dashtty_mutex);
+
+ if (line == CONSOLE_CHANNEL)
+ return;
+
+ num_channels_need_poll--;
+
+ if (num_channels_need_poll <= 0)
+ del_timer(&poll_timer);
+}
+
+static int dashtty_write(struct tty_struct *tty, const unsigned char *buf,
+ int count)
+{
+ struct dashtty *dtty;
+ struct dashbuf *dbuf;
+ int channel;
+
+ if (count <= 0)
+ return 0;
+
+ /* Determine the channel */
+ channel = FIRST_TTY_CHANNEL + tty->index;
+ dtty = dashtty_ttys[channel];
+ BUG_ON(!dtty);
+
+ dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
+ if (!dbuf)
+ return 0;
+
+ dbuf->buf = kzalloc(count, GFP_KERNEL);
+ if (!dbuf->buf) {
+ kfree(dbuf);
+ return 0;
+ }
+
+ memcpy(dbuf->buf, buf, count);
+ dbuf->count = count;
+ dbuf->chan = channel;
+ dbuf->tty = dtty;
+
+ /*
+ * Enqueue the output buffer.
+ *
+ * The reason that we asynchronously write the buffer is because
+ * there's no way to tell what CPU we're currently executing on.
+ * If we were to write the buffer synchornously then because dash
+ * 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(&dashtty_q_lock);
+ list_add_tail(&dbuf->entry, &dashtty_output_queue);
+ spin_unlock(&dashtty_q_lock);
+
+ wake_up_interruptible(&dashtty_waitqueue);
+
+ /*
+ * FIXME: This is slightly optimistic. Because we're deferring
+ * the output until later it is impossible to predict whether we
+ * will actually write "count" bytes.
+ */
+ return count;
+}
+
+/*
+ * Ask the stub how much room there is in the channel
+ */
+static int dashtty_write_room(struct tty_struct *tty)
+{
+ unsigned int data[2];
+ static unsigned int actual_space;
+ int channel;
+
+ if (actual_space)
+ return actual_space;
+
+ channel = FIRST_TTY_CHANNEL + tty->index;
+
+ /* Is there any data waiting ? */
+ if (chancall(RDSTAT, channel, 0, NULL, &data[0]) == CONAOK) {
+ /* There was a bug in LogieDash (1.2.8a at least) where
+ * the two values were returned the WRONG WAY AROUND!!!
+ */
+ actual_space = data[1];
+ }
+
+ return actual_space;
+}
+
+static int dashtty_chars_in_buffer(struct tty_struct *tty)
+{
+ return 0; /* we're not buffering */
+}
+
+static const struct tty_operations dashtty_ops = {
+ .open = dashtty_open,
+ .close = dashtty_close,
+ .write = dashtty_write,
+ .write_room = dashtty_write_room,
+ .chars_in_buffer = dashtty_chars_in_buffer,
+};
+
+static int __init dashtty_init(void)
+{
+ int ret;
+ int nport;
+
+ if (!metag_da_enabled())
+ return -ENODEV;
+
+ channel_driver = tty_alloc_driver(NUM_TTY_CHANNELS, 0);
+ if (IS_ERR(channel_driver))
+ return PTR_ERR(channel_driver);
+
+ channel_driver->owner = THIS_MODULE;
+ channel_driver->driver_name = "ttyDA";
+ channel_driver->name = "ttyDA";
+ channel_driver->major = DA_TTY_MAJOR;
+ channel_driver->minor_start = 0;
+ channel_driver->type = TTY_DRIVER_TYPE_SERIAL;
+ channel_driver->subtype = SERIAL_TYPE_NORMAL;
+ channel_driver->init_termios = tty_std_termios;
+ channel_driver->init_termios.c_cflag =
+ B38400 | CS8 | CREAD | HUPCL | CLOCAL;
+ channel_driver->flags = TTY_DRIVER_REAL_RAW;
+
+ tty_set_operations(channel_driver, &dashtty_ops);
+ for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
+ tty_port_init(&dashtty_ports[nport]);
+ tty_port_link_device(&dashtty_ports[nport], channel_driver,
+ nport);
+ }
+
+ spin_lock_init(&dashtty_q_lock);
+ INIT_LIST_HEAD(&dashtty_output_queue);
+ init_waitqueue_head(&dashtty_waitqueue);
+ dashtty_thread = kthread_create(put_data, NULL, "ttyDA");
+ if (IS_ERR(dashtty_thread)) {
+ pr_info("Couldn't create dashtty thread\n");
+ return PTR_ERR(dashtty_thread);
+ }
+ kthread_bind(dashtty_thread, 0);
+ wake_up_process(dashtty_thread);
+
+ ret = tty_register_driver(channel_driver);
+
+ if (ret < 0) {
+ pr_info("Couldn't install dashtty driver: err %d\n",
+ ret);
+ put_tty_driver(channel_driver);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void dashtty_exit(void)
+{
+ kthread_stop(dashtty_thread);
+ del_timer(&poll_timer);
+ tty_unregister_driver(channel_driver);
+ put_tty_driver(channel_driver);
+}
+
+module_init(dashtty_init);
+module_exit(dashtty_exit);
+
+#ifdef CONFIG_DA_CONSOLE
+
+static void dash_console_write(struct console *co, const char *s,
+ unsigned int count)
+{
+ int actually_written;
+
+ chancall(WRBUF, CONSOLE_CHANNEL, count, (void *)s, &actually_written);
+}
+
+static struct tty_driver *dash_console_device(struct console *c, int *index)
+{
+ *index = c->index;
+ return channel_driver;
+}
+
+struct console dash_console = {
+ .name = "ttyDA",
+ .write = dash_console_write,
+ .device = dash_console_device,
+ .flags = CON_PRINTBUFFER,
+ .index = 1,
+};
+
+#endif
--
1.7.7.6


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