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Date: Tue, 17 Nov 2015 15:34:34 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Baolin Wang <baolin.wang@...aro.org>
Cc: Felipe Balbi <balbi@...com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
r.baldyga@...sung.com, fabio.estevam@...escale.com,
Philip.Oberstaller@...tentrio.com,
Peter Hurley <peter@...leysoftware.com>,
scottwood@...escale.com, Mark Brown <broonie@...nel.org>,
USB <linux-usb@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: gadget: Add the console support for usb-to-serial port
On Mon, Nov 16, 2015 at 9:05 AM, Baolin Wang <baolin.wang@...aro.org> wrote:
> It dose not work when we want to use the usb-to-serial port based
> on one usb gadget as a console. Thus this patch adds the console
> initialization to support this request.
> @@ -79,6 +80,16 @@
> */
> #define QUEUE_SIZE 16
> #define WRITE_BUF_SIZE 8192 /* TX only */
> +#define GS_BUFFER_SIZE (4096)
Redundant parens
> +#define GS_CONSOLE_BUF_SIZE (2 * GS_BUFFER_SIZE)
> +
> +struct gscons_info {
> + struct gs_port *port;
> + struct tty_driver *tty_driver;
> + struct work_struct work;
> + int buf_tail;
> + char buf[GS_CONSOLE_BUF_SIZE];
Can't be malloced once?
> +static struct usb_request *gs_request_new(struct usb_ep *ep, int buffer_size)
> +{
> + struct usb_request *req = usb_ep_alloc_request(ep, GFP_ATOMIC);
> +
> + if (!req)
For sake of readability it's better to have assignment explicitly before 'if'.
> + return NULL;
> +
> + /* now allocate buffers for the requests */
> + req->buf = kmalloc(buffer_size, GFP_ATOMIC);
> + if (!req->buf) {
> + usb_ep_free_request(ep, req);
> + return NULL;
> + }
> +
> + return req;
> +}
> +
> +static void gs_request_free(struct usb_request *req, struct usb_ep *ep)
> +{
> + if (req) {
if (!req)
return;
?
> + kfree(req->buf);
> + usb_ep_free_request(ep, req);
> + }
> +}
> +
> +static void gs_complete_out(struct usb_ep *ep, struct usb_request *req)
> +{
> + if (req->status != 0 && req->status != -ECONNRESET)
> + return;
Something missed here. Currently it's no-op.
> +}
> +
> +static struct console gserial_cons;
> +static int gs_console_connect(void)
> +{
> + struct gscons_info *info = gserial_cons.data;
> + int port_num = gserial_cons.index;
> + struct usb_request *req;
> + struct gs_port *port;
> + struct usb_ep *ep;
> +
> + if (port_num >= MAX_U_SERIAL_PORTS || port_num < 0) {
> + pr_err("%s: port num [%d] exceeds the range.\n",
> + __func__, port_num);
> + return -ENXIO;
> + }
> +
> + port = ports[port_num].port;
> + if (!port) {
> + pr_err("%s: serial line [%d] not allocated.\n",
> + __func__, port_num);
> + return -ENODEV;
> + }
> +
> + if (!port->port_usb) {
> + pr_err("%s: no port usb.\n", __func__);
Starting from here could it be dev_err and so on?
> + return -ENODEV;
> + }
> +
> + ep = port->port_usb->in;
> + if (!ep) {
> + pr_err("%s: no usb endpoint.\n", __func__);
> + return -ENXIO;
> + }
> +
> + req = port->console_req;
> + if (!req) {
> + req = gs_request_new(ep, GS_BUFFER_SIZE);
> + if (!req) {
> + pr_err("%s: request fail.\n", __func__);
> + return -ENOMEM;
> + }
> + req->complete = gs_complete_out;
> + }
> +
> + info->port = port;
> +
> + pr_debug("%s: port[%d] console connect!\n", __func__, port_num);
Dynamic debug will add function name if asked.
> + return 0;
> +}
> +
> +static void gs_console_work(struct work_struct *work)
> +{
> + struct gscons_info *info = container_of(work, struct gscons_info, work);
> + struct gs_port *port = info->port;
> + struct usb_request *req;
> + struct usb_ep *ep;
> + int xfer, ret, count;
> + char *p;
> +
> + if (!port || !port->port_usb)
> + return;
> +
> + req = port->console_req;
> + ep = port->port_usb->in;
> + if (!req || !ep)
> + return;
> +
> + spin_lock_irq(&port->port_lock);
> + count = info->buf_tail;
> + p = info->buf;
> +
> + while (count > 0 && !port->write_busy) {
> + if (count > GS_BUFFER_SIZE)
> + xfer = GS_BUFFER_SIZE;
> + else
> + xfer = count;
xfer = min_t(…, count, GS_BUFFER_SIZE);
> +
> + memcpy(req->buf, p, xfer);
> + req->length = xfer;
> +
> + port->write_busy = true;
> + spin_unlock(&port->port_lock);
> + ret = usb_ep_queue(ep, req, GFP_ATOMIC);
> + spin_lock(&port->port_lock);
> + port->write_busy = false;
> + if (ret < 0)
> + break;
> +
> + p += xfer;
> + count -= xfer;
> + }
> +
> + info->buf_tail -= count;
> + spin_unlock_irq(&port->port_lock);
> +}
> +
> +static int gs_console_setup(struct console *co, char *options)
> +{
> + struct gscons_info *gscons_info;
> +
> + gscons_info = kzalloc(sizeof(struct gscons_info), GFP_KERNEL);
> + if (!gscons_info)
> + return -ENOMEM;
> +
> + gscons_info->port = NULL;
> + gscons_info->tty_driver = gs_tty_driver;
> + INIT_WORK(&gscons_info->work, gs_console_work);
> + gscons_info->buf_tail = 0;
> + co->data = gscons_info;
> +
> + return 0;
> +}
> +
> +static void gs_console_write(struct console *co,
> + const char *buf, unsigned count)
> +{
> + struct gscons_info *info = co->data;
> + int avail, xfer;
> + char *p;
> +
> + avail = GS_CONSOLE_BUF_SIZE - info->buf_tail;
> + if (count > avail)
> + xfer = avail;
> + else
> + xfer = count;
Ditto.
> +
> + p = &info->buf[info->buf_tail];
> + memcpy(p, buf, xfer);
> + info->buf_tail += xfer;
> +
> + schedule_work(&info->work);
> +}
> +
> +static struct tty_driver *gs_console_device(struct console *co, int *index)
> +{
> + struct gscons_info *info = co->data;
> +
> + *index = co->index;
> + return info->tty_driver;
> +}
> +
> +static struct console gserial_cons = {
> + .name = "ttyGS",
> + .write = gs_console_write,
> + .device = gs_console_device,
> + .setup = gs_console_setup,
> + .flags = CON_PRINTBUFFER,
> + .index = -1,
> +};
> +
> +static void gserial_console_init(void)
> +{
> + register_console(&gserial_cons);
> +}
> +
> +static void gserial_console_exit(void)
> +{
> + struct gscons_info *info = gserial_cons.data;
> + struct gs_port *port = info->port;
> + struct usb_request *req;
> + struct usb_ep *ep;
> +
> + if (port && port->port_usb) {
> + req = port->console_req;
> + ep = port->port_usb->in;
> + gs_request_free(req, ep);
> + }
> +
> + kfree(info);
> + unregister_console(&gserial_cons);
> +}
> +
> +#else
> +
> +static int gs_console_connect(void)
> +{
> + return 0;
> +}
> +
> +static void gserial_console_init(void)
> +{
> +}
> +
> +static void gserial_console_exit(void)
> +{
> +}
> +
> +#endif
> +
> /**
> * gserial_connect - notify TTY I/O glue that USB link is active
> * @gser: the function, set up with endpoints and descriptors
> @@ -1219,6 +1453,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
> gser->disconnect(gser);
> }
>
> + status = gs_console_connect();
> spin_unlock_irqrestore(&port->port_lock, flags);
>
> return status;
> @@ -1320,6 +1555,8 @@ static int userial_init(void)
> goto fail;
> }
>
> + gserial_console_init();
> +
> pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
> MAX_U_SERIAL_PORTS,
> (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
> @@ -1334,6 +1571,7 @@ module_init(userial_init);
>
> static void userial_cleanup(void)
> {
> + gserial_console_exit();
> tty_unregister_driver(gs_tty_driver);
> put_tty_driver(gs_tty_driver);
> gs_tty_driver = NULL;
> --
> 1.7.9.5
>
> --
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--
With Best Regards,
Andy Shevchenko
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