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Subject[RFC PATCH v2 6/6] serial: uartps: Remove CDNS_UART_NR_PORTS macro
Date
This patch is removing CDNS_UART_NR_PORTS macro which limits number of
ports which can be used. Every instance is registering own struct
uart_driver with minor number which corresponds to alias ID (or 0 now).
and with 1 uart port. The same alias ID is saved to
tty_driver->name_base which is key field for creating ttyPSX name.

Because name_base and minor number are setup already there is no need to
setup any port->line number because 0 is the right value.

~# find /proc/tty/ -name "*uartps*"
/proc/tty/driver/xuartps0
/proc/tty/driver/xuartps100

Unfortunately this driver is setting up major number to 0 for using
dynamic assignment and kernel is allocating different major numbers for
every instance instead of using the same major and different minor
number.

~# ls -la /dev/ttyPS*
crw------- 1 root root 252, 0 Jan 1 03:36 /dev/ttyPS0
crw--w---- 1 root root 253, 1 Jan 1 00:00 /dev/ttyPS1

When major number is not 0. For example 252 then major/minor
combinations are in expected form

~# ls -la /dev/ttyPS*
crw------- 1 root root 252, 0 Jan 1 04:04 /dev/ttyPS0
crw--w---- 1 root root 252, 1 Jan 1 00:00 /dev/ttyPS1

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

Changes in v2:
- Register one uart_driver with unique minor at probe time

This patch not done because id is not unique. This needs to be solved
before this patch can be applied. In v1 I have created
of_alias_check_id() for that. https://lkml.org/lkml/2018/4/26/551

Also we need to run more testing on this to make sure that everything is
working properly.

---
drivers/tty/serial/xilinx_uartps.c | 78 +++++++++++++++++++++++---------------
1 file changed, 48 insertions(+), 30 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index d76efe8cb3df..82cc17ec7b5d 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -30,8 +30,6 @@
#define CDNS_UART_TTY_NAME "ttyPS"
#define CDNS_UART_NAME "xuartps"
#define CDNS_UART_MAJOR 0 /* use dynamic node allocation */
-#define CDNS_UART_MINOR 0 /* works best with devtmpfs */
-#define CDNS_UART_NR_PORTS 2
#define CDNS_UART_FIFO_SIZE 64 /* FIFO size */
#define CDNS_UART_REGISTER_SPACE 0x1000

@@ -1247,8 +1245,6 @@ static int __init cdns_uart_console_setup(struct console *co, char *options)
return uart_set_options(port, co, baud, parity, bits, flow);
}

-static struct uart_driver cdns_uart_uart_driver;
-
static struct console cdns_uart_console = {
.name = CDNS_UART_TTY_NAME,
.write = cdns_uart_console_write,
@@ -1256,7 +1252,6 @@ static int __init cdns_uart_console_setup(struct console *co, char *options)
.setup = cdns_uart_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1, /* Specified on the cmdline (e.g. console=ttyPS ) */
- .data = &cdns_uart_uart_driver,
};
#endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */

@@ -1419,6 +1414,8 @@ static int cdns_uart_probe(struct platform_device *pdev)
struct resource *res;
struct cdns_uart *cdns_uart_data;
const struct of_device_id *match;
+ struct uart_driver *cdns_uart_uart_driver;
+ char *driver_name;

cdns_uart_data = devm_kzalloc(&pdev->dev, sizeof(*cdns_uart_data),
GFP_KERNEL);
@@ -1431,32 +1428,49 @@ static int cdns_uart_probe(struct platform_device *pdev)
/* Look for a serialN alias */
id = of_alias_get_id(pdev->dev.of_node, "serial");
if (id < 0)
+ /*
+ * FIXME this is not enough because if there the next instance
+ * without alias it will get also id = 0 which is wrong
+ */
id = 0;

- if (id >= CDNS_UART_NR_PORTS) {
- dev_err(&pdev->dev, "Cannot get uart_port structure\n");
- return -ENODEV;
- }
+ cdns_uart_uart_driver = devm_kzalloc(&pdev->dev,
+ sizeof(*cdns_uart_uart_driver),
+ GFP_KERNEL);
+ if (!cdns_uart_uart_driver)
+ return -ENOMEM;
+
+ /* There is a need to use unique driver name */
+ driver_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s%d",
+ CDNS_UART_NAME, id);
+ if (!driver_name)
+ return -ENOMEM;

- if (!cdns_uart_uart_driver.state) {
- cdns_uart_uart_driver.owner = THIS_MODULE,
- cdns_uart_uart_driver.driver_name = CDNS_UART_NAME,
- cdns_uart_uart_driver.dev_name = CDNS_UART_TTY_NAME,
- cdns_uart_uart_driver.major = CDNS_UART_MAJOR,
- cdns_uart_uart_driver.minor = CDNS_UART_MINOR,
- cdns_uart_uart_driver.nr = CDNS_UART_NR_PORTS,
+ cdns_uart_uart_driver->owner = THIS_MODULE;
+ cdns_uart_uart_driver->driver_name = driver_name;
+ cdns_uart_uart_driver->dev_name = CDNS_UART_TTY_NAME;
+ cdns_uart_uart_driver->major = CDNS_UART_MAJOR;
+ cdns_uart_uart_driver->minor = id;
+ cdns_uart_uart_driver->nr = 1;
#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
- cdns_uart_uart_driver.cons = &cdns_uart_console,
+ cdns_uart_uart_driver->cons = &cdns_uart_console;
+ cdns_uart_console.data = cdns_uart_uart_driver;
#endif

- rc = uart_register_driver(&cdns_uart_uart_driver);
- if (rc < 0) {
- dev_err(&pdev->dev, "Failed to register driver\n");
- return rc;
- }
+ rc = uart_register_driver(cdns_uart_uart_driver);
+ if (rc < 0) {
+ dev_err(&pdev->dev, "Failed to register driver\n");
+ return rc;
}

- cdns_uart_data->cdns_uart_driver = &cdns_uart_uart_driver;
+ /*
+ * Setting up proper name_base needs to be done after uart
+ * registration because tty_driver structure is not filled.
+ * name_base is 0 by default.
+ */
+ cdns_uart_uart_driver->tty_driver->name_base = id;
+
+ cdns_uart_data->cdns_uart_driver = cdns_uart_uart_driver;

match = of_match_node(cdns_uart_of_match, pdev->dev.of_node);
if (match && match->data) {
@@ -1473,7 +1487,8 @@ static int cdns_uart_probe(struct platform_device *pdev)
}
if (IS_ERR(cdns_uart_data->pclk)) {
dev_err(&pdev->dev, "pclk clock not found.\n");
- return PTR_ERR(cdns_uart_data->pclk);
+ rc = PTR_ERR(cdns_uart_data->pclk);
+ goto err_out_unregister_driver;
}

cdns_uart_data->uartclk = devm_clk_get(&pdev->dev, "uart_clk");
@@ -1484,13 +1499,14 @@ static int cdns_uart_probe(struct platform_device *pdev)
}
if (IS_ERR(cdns_uart_data->uartclk)) {
dev_err(&pdev->dev, "uart_clk clock not found.\n");
- return PTR_ERR(cdns_uart_data->uartclk);
+ rc = PTR_ERR(cdns_uart_data->uartclk);
+ goto err_out_unregister_driver;
}

rc = clk_prepare_enable(cdns_uart_data->pclk);
if (rc) {
dev_err(&pdev->dev, "Unable to enable pclk clock.\n");
- return rc;
+ goto err_out_unregister_driver;
}
rc = clk_prepare_enable(cdns_uart_data->uartclk);
if (rc) {
@@ -1525,7 +1541,6 @@ static int cdns_uart_probe(struct platform_device *pdev)
port->flags = UPF_BOOT_AUTOCONF;
port->ops = &cdns_uart_ops;
port->fifosize = CDNS_UART_FIFO_SIZE;
- port->line = id;

/*
* Register the port.
@@ -1552,11 +1567,11 @@ static int cdns_uart_probe(struct platform_device *pdev)
* If register_console() don't assign value, then console_port pointer
* is cleanup.
*/
- if (cdns_uart_uart_driver.cons->index == -1)
+ if (cdns_uart_uart_driver->cons->index == -1)
console_port = port;
#endif

- rc = uart_add_one_port(&cdns_uart_uart_driver, port);
+ rc = uart_add_one_port(cdns_uart_uart_driver, port);
if (rc) {
dev_err(&pdev->dev,
"uart_add_one_port() failed; err=%i\n", rc);
@@ -1565,7 +1580,7 @@ static int cdns_uart_probe(struct platform_device *pdev)

#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
/* This is not port which is used for console that's why clean it up */
- if (cdns_uart_uart_driver.cons->index == -1)
+ if (cdns_uart_uart_driver->cons->index == -1)
console_port = NULL;
#endif

@@ -1583,6 +1598,8 @@ static int cdns_uart_probe(struct platform_device *pdev)
clk_disable_unprepare(cdns_uart_data->uartclk);
err_out_clk_dis_pclk:
clk_disable_unprepare(cdns_uart_data->pclk);
+err_out_unregister_driver:
+ uart_unregister_driver(cdns_uart_data->cdns_uart_driver);

return rc;
}
@@ -1611,6 +1628,7 @@ static int cdns_uart_remove(struct platform_device *pdev)
pm_runtime_disable(&pdev->dev);
pm_runtime_set_suspended(&pdev->dev);
pm_runtime_dont_use_autosuspend(&pdev->dev);
+ uart_unregister_driver(cdns_uart_data->cdns_uart_driver);
return rc;
}

--
1.9.1
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