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Subject[PATCH v2 2/2] serial: sh-sci: Move uart_register_driver call to device probe
Date
uart_register_driver call binds the driver to a specific device
node through tty_register_driver call. This should typically
happen during device probe call.

In a multiplatform scenario, it is possible that multiple serial
drivers are part of the kernel. Currently the driver registration fails
if multiple serial drivers with overlapping major/minor numbers are
included.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

---

Changes in v2:
- Add locking to prevent issues when two probes run in parallel

drivers/tty/serial/sh-sci.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 9a47cc4f16a2..f23254add9a7 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -2935,6 +2935,7 @@ static inline int sci_probe_earlyprintk(struct platform_device *pdev)

static const char banner[] __initconst = "SuperH (H)SCI(F) driver initialized";

+static DEFINE_MUTEX(sci_uart_registration_lock);
static struct uart_driver sci_uart_driver = {
.owner = THIS_MODULE,
.driver_name = "sci",
@@ -3063,6 +3064,16 @@ static int sci_probe_single(struct platform_device *dev,
return -EINVAL;
}

+ mutex_lock(&sci_uart_registration_lock);
+ if (!sci_uart_driver.state) {
+ ret = uart_register_driver(&sci_uart_driver);
+ if (ret) {
+ mutex_unlock(&sci_uart_registration_lock);
+ return ret;
+ }
+ }
+ mutex_unlock(&sci_uart_registration_lock);
+
ret = sci_init_single(dev, sciport, index, p, false);
if (ret)
return ret;
@@ -3186,24 +3197,17 @@ static struct platform_driver sci_driver = {

static int __init sci_init(void)
{
- int ret;
-
pr_info("%s\n", banner);

- ret = uart_register_driver(&sci_uart_driver);
- if (likely(ret == 0)) {
- ret = platform_driver_register(&sci_driver);
- if (unlikely(ret))
- uart_unregister_driver(&sci_uart_driver);
- }
-
- return ret;
+ return platform_driver_register(&sci_driver);
}

static void __exit sci_exit(void)
{
platform_driver_unregister(&sci_driver);
- uart_unregister_driver(&sci_uart_driver);
+
+ if (sci_uart_driver.state)
+ uart_unregister_driver(&sci_uart_driver);
}

#ifdef CONFIG_SERIAL_SH_SCI_CONSOLE
--
2.11.0
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