greybus: Dump log from APB1

On AP module (form factor), we don't have access to APBridge JTAG or UART.
But sometime, we still need to get log from APBridge. Add a new request in control endpoint
to get APBridge logs.
Logs can be accessed using debugfs (greybus/apb1_log).

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/greybus/es1.c b/drivers/staging/greybus/es1.c
index bbf1bd1048be03d96232b37de2cc3786a0a3aa3a..9ad8a76d33ac50841e3417f4532a6fa56b826d95 100644 (file)
--- a/drivers/staging/greybus/es1.c
+++ b/drivers/staging/greybus/es1.c
@@ -8,10 +8,14 @@
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/kthread.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <linux/sizes.h>
 #include <linux/usb.h>
+#include <linux/kfifo.h>
+#include <linux/debugfs.h>
+#include <asm/uaccess.h>
 
 #include "greybus.h"
 #include "svc_msg.h"
@@ -35,6 +39,12 @@ static const struct usb_device_id id_table[] = {
 };
 MODULE_DEVICE_TABLE(usb, id_table);
 
+#define APB1_LOG_SIZE          SZ_16K
+static struct dentry *apb1_log_dentry;
+static struct dentry *apb1_log_enable_dentry;
+static struct task_struct *apb1_log_task;
+static DEFINE_KFIFO(apb1_log_fifo, char, APB1_LOG_SIZE);
+
 /*
  * Number of CPort IN urbs in flight at any point in time.
  * Adjust if we are having stalls in the USB buffer due to not enough urbs in
@@ -91,6 +101,7 @@ static inline struct es1_ap_dev *hd_to_es1(struct greybus_host_device *hd)
 }
 
 static void cport_out_callback(struct urb *urb);
+static void usb_log_enable(struct es1_ap_dev *es1, int enable);
 
 /*
  * Buffer constraints for the host driver.
@@ -326,6 +337,8 @@ static void ap_disconnect(struct usb_interface *interface)
        if (!es1)
                return;
 
+       usb_log_enable(es1, 0);
+
        /* Tear down everything! */
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                struct urb *urb = es1->cport_out_urb[i];
@@ -474,6 +487,125 @@ static void cport_out_callback(struct urb *urb)
         */
 }
 
+static void apb1_log_get(struct es1_ap_dev *es1)
+{
+       char buf[65];
+       int retval;
+
+       /* SVC messages go down our control pipe */
+       do {
+               memset(buf, 0, 65);
+               retval = usb_control_msg(es1->usb_dev,
+                                       usb_rcvctrlpipe(es1->usb_dev,
+                                                       es1->control_endpoint),
+                                       0x02,   /* vendor request APB1 log */
+                                       USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
+                                       0x00, 0x00,
+                                       buf,
+                                       64,
+                                       ES1_TIMEOUT);
+               if (retval > 0)
+                       kfifo_in(&apb1_log_fifo, buf, retval);
+       } while (retval > 0);
+}
+
+static int apb1_log_poll(void *data)
+{
+       while (!kthread_should_stop()) {
+               msleep(1000);
+               apb1_log_get((struct es1_ap_dev *)data);
+       }
+       return 0;
+}
+
+static ssize_t apb1_log_read(struct file *f, char __user *buf,
+                               size_t count, loff_t *ppos)
+{
+       ssize_t ret;
+       size_t copied;
+       char *tmp_buf;
+
+       if (count > APB1_LOG_SIZE)
+               count = APB1_LOG_SIZE;
+
+       tmp_buf = kmalloc(count, GFP_KERNEL);
+       if (!tmp_buf)
+               return -ENOMEM;
+
+       copied = kfifo_out(&apb1_log_fifo, tmp_buf, count);
+       ret = simple_read_from_buffer(buf, count, ppos, tmp_buf, copied);
+
+       kfree(tmp_buf);
+
+       return ret;
+}
+
+static struct file_operations apb1_log_fops = {
+       .read   = apb1_log_read,
+};
+
+static void usb_log_enable(struct es1_ap_dev *es1, int enable)
+{
+       if (enable && apb1_log_task != NULL)
+               return;
+
+       if (enable) {
+               /* get log from APB1 */
+               apb1_log_task = kthread_run(apb1_log_poll, es1, "apb1_log");
+               if (apb1_log_task == ERR_PTR(-ENOMEM))
+                       return;
+               apb1_log_dentry = debugfs_create_file("apb1_log", 444,
+                                                       gb_debugfs_get(), NULL,
+                                                       &apb1_log_fops);
+       } else {
+               if (apb1_log_dentry) {
+                       debugfs_remove(apb1_log_dentry);
+                       apb1_log_dentry = NULL;
+               }
+
+               if (apb1_log_task) {
+                       kthread_stop(apb1_log_task);
+                       apb1_log_task = NULL;
+               }
+       }
+}
+
+static ssize_t apb1_log_enable_read(struct file *f, char __user *buf,
+                               size_t count, loff_t *ppos)
+{
+       char tmp_buf[3];
+       int enable = apb1_log_task != NULL;
+       sprintf(tmp_buf, "%d\n", enable);
+       return simple_read_from_buffer(buf, count, ppos, tmp_buf, 3);
+}
+
+static ssize_t apb1_log_enable_write(struct file *f, char __user *buf,
+                               size_t count, loff_t *ppos)
+{
+       int enable;
+       char *tmp_buf;
+       ssize_t retval = -EINVAL;
+       struct es1_ap_dev *es1 = (struct es1_ap_dev *)f->f_inode->i_private;
+
+       tmp_buf = kmalloc(count, GFP_KERNEL);
+       if (!tmp_buf)
+               return -ENOMEM;
+
+       copy_from_user(tmp_buf, buf, count);
+       if (sscanf(tmp_buf, "%d", &enable) == 1) {
+               usb_log_enable(es1, enable);
+               retval = count;
+       }
+       kfree(tmp_buf);
+       
+       return retval;
+}
+
+static struct file_operations apb1_log_enable_fops = {
+       .read   = apb1_log_enable_read,
+       .write  = apb1_log_enable_write,
+};
+
 /*
  * The ES1 USB Bridge device contains 4 endpoints
  * 1 Control - usual USB stuff + AP -> SVC messages
@@ -600,6 +732,10 @@ static int ap_probe(struct usb_interface *interface,
        if (retval)
                goto error;
 
+       apb1_log_enable_dentry = debugfs_create_file("apb1_log_enable", 666,
+                                                       gb_debugfs_get(), es1,
+                                                       &apb1_log_enable_fops);
+
        return 0;
 error:
        ap_disconnect(interface);