Revert "serial: uartps: Change uart ID port allocation"

This reverts commit ae1cca3fa3478be92948dbbcd722390272032ade.

With setting up NR_PORTS to 16 to be able to use serial2 and higher
aliases and don't loose functionality which was intended by these changes.

As Johan says, this driver needs a lot more work and these changes are
only going in the wrong direction:
  https://lkml.kernel.org/r/20190523091839.GC568@localhost

Reported-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/a94931b65ce0089f76fb1fe6b446a08731bff754.1585905873.git.michal.simek@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 9db3cd1..58f0fa0 100644 (file)
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -27,6 +27,7 @@
 #define CDNS_UART_TTY_NAME     "ttyPS"
 #define CDNS_UART_NAME         "xuartps"
 #define CDNS_UART_MAJOR                0       /* use dynamic node allocation */
+#define CDNS_UART_NR_PORTS     16
 #define CDNS_UART_FIFO_SIZE    64      /* FIFO size */
 #define CDNS_UART_REGISTER_SPACE       0x1000
 #define TX_TIMEOUT             500000
@@ -1403,90 +1404,6 @@ static const struct of_device_id cdns_uart_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, cdns_uart_of_match);
 
-/*
- * Maximum number of instances without alias IDs but if there is alias
- * which target "< MAX_UART_INSTANCES" range this ID can't be used.
- */
-#define MAX_UART_INSTANCES     32
-
-/* Stores static aliases list */
-static DECLARE_BITMAP(alias_bitmap, MAX_UART_INSTANCES);
-static int alias_bitmap_initialized;
-
-/* Stores actual bitmap of allocated IDs with alias IDs together */
-static DECLARE_BITMAP(bitmap, MAX_UART_INSTANCES);
-/* Protect bitmap operations to have unique IDs */
-static DEFINE_MUTEX(bitmap_lock);
-
-static int cdns_get_id(struct platform_device *pdev)
-{
-       int id, ret;
-
-       mutex_lock(&bitmap_lock);
-
-       /* Alias list is stable that's why get alias bitmap only once */
-       if (!alias_bitmap_initialized) {
-               ret = of_alias_get_alias_list(cdns_uart_of_match, "serial",
-                                             alias_bitmap, MAX_UART_INSTANCES);
-               if (ret && ret != -EOVERFLOW) {
-                       mutex_unlock(&bitmap_lock);
-                       return ret;
-               }
-
-               alias_bitmap_initialized++;
-       }
-
-       /* Make sure that alias ID is not taken by instance without alias */
-       bitmap_or(bitmap, bitmap, alias_bitmap, MAX_UART_INSTANCES);
-
-       dev_dbg(&pdev->dev, "Alias bitmap: %*pb\n",
-               MAX_UART_INSTANCES, bitmap);
-
-       /* Look for a serialN alias */
-       id = of_alias_get_id(pdev->dev.of_node, "serial");
-       if (id < 0) {
-               dev_warn(&pdev->dev,
-                        "No serial alias passed. Using the first free id\n");
-
-               /*
-                * Start with id 0 and check if there is no serial0 alias
-                * which points to device which is compatible with this driver.
-                * If alias exists then try next free position.
-                */
-               id = 0;
-
-               for (;;) {
-                       dev_info(&pdev->dev, "Checking id %d\n", id);
-                       id = find_next_zero_bit(bitmap, MAX_UART_INSTANCES, id);
-
-                       /* No free empty instance */
-                       if (id == MAX_UART_INSTANCES) {
-                               dev_err(&pdev->dev, "No free ID\n");
-                               mutex_unlock(&bitmap_lock);
-                               return -EINVAL;
-                       }
-
-                       dev_dbg(&pdev->dev, "The empty id is %d\n", id);
-                       /* Check if ID is empty */
-                       if (!test_and_set_bit(id, bitmap)) {
-                               /* Break the loop if bit is taken */
-                               dev_dbg(&pdev->dev,
-                                       "Selected ID %d allocation passed\n",
-                                       id);
-                               break;
-                       }
-                       dev_dbg(&pdev->dev,
-                               "Selected ID %d allocation failed\n", id);
-                       /* if taking bit fails then try next one */
-                       id++;
-               }
-       }
-
-       mutex_unlock(&bitmap_lock);
-
-       return id;
-}
-
 /**
  * cdns_uart_probe - Platform driver probe
  * @pdev: Pointer to the platform device structure
@@ -1520,17 +1437,21 @@ static int cdns_uart_probe(struct platform_device *pdev)
        if (!cdns_uart_uart_driver)
                return -ENOMEM;
 
-       cdns_uart_data->id = cdns_get_id(pdev);
+       /* Look for a serialN alias */
+       cdns_uart_data->id = of_alias_get_id(pdev->dev.of_node, "serial");
        if (cdns_uart_data->id < 0)
-               return cdns_uart_data->id;
+               cdns_uart_data->id = 0;
+
+       if (cdns_uart_data->id >= CDNS_UART_NR_PORTS) {
+               dev_err(&pdev->dev, "Cannot get uart_port structure\n");
+               return -ENODEV;
+       }
 
        /* There is a need to use unique driver name */
        driver_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s%d",
                                     CDNS_UART_NAME, cdns_uart_data->id);
-       if (!driver_name) {
-               rc = -ENOMEM;
-               goto err_out_id;
-       }
+       if (!driver_name)
+               return -ENOMEM;
 
        cdns_uart_uart_driver->owner = THIS_MODULE;
        cdns_uart_uart_driver->driver_name = driver_name;
@@ -1559,7 +1480,7 @@ static int cdns_uart_probe(struct platform_device *pdev)
        rc = uart_register_driver(cdns_uart_uart_driver);
        if (rc < 0) {
                dev_err(&pdev->dev, "Failed to register driver\n");
-               goto err_out_id;
+               return rc;
        }
 
        cdns_uart_data->cdns_uart_driver = cdns_uart_uart_driver;
@@ -1710,10 +1631,7 @@ 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);
-err_out_id:
-       mutex_lock(&bitmap_lock);
-       clear_bit(cdns_uart_data->id, bitmap);
-       mutex_unlock(&bitmap_lock);
+
        return rc;
 }
 
@@ -1736,9 +1654,6 @@ static int cdns_uart_remove(struct platform_device *pdev)
 #endif
        rc = uart_remove_one_port(cdns_uart_data->cdns_uart_driver, port);
        port->mapbase = 0;
-       mutex_lock(&bitmap_lock);
-       clear_bit(cdns_uart_data->id, bitmap);
-       mutex_unlock(&bitmap_lock);
        clk_disable_unprepare(cdns_uart_data->uartclk);
        clk_disable_unprepare(cdns_uart_data->pclk);
        pm_runtime_disable(&pdev->dev);