[PATCHv4 2/4] tty: serial: uartlite: Add clock adaptation

[Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxxxxx>]

Add support of Common Clock Framework for Uartlite driver.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxxxxx>
---
v2:
removed the suspend resume changes to separate driver

 drivers/tty/serial/uartlite.c | 49 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index 0f798f7..b3a12be 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c
@@ -21,6 +21,7 @@
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_platform.h>
+#include <linux/clk.h>

 #define ULITE_NAME             "ttyUL"
 #define ULITE_MAJOR            204
@@ -56,6 +57,7 @@

 struct uartlite_data {
        const struct uartlite_reg_ops *reg_ops;
+       struct clk *clk;
 };

 struct uartlite_reg_ops {
@@ -261,8 +263,15 @@ static void ulite_break_ctl(struct uart_port *port, int ctl)

 static int ulite_startup(struct uart_port *port)
 {
+       struct uartlite_data *pdata = port->private_data;
        int ret;

+       ret = clk_enable(pdata->clk);
+       if (ret) {
+               dev_err(port->dev, "Failed to enable clock\n");
+               return ret;
+       }
+
        ret = request_irq(port->irq, ulite_isr, IRQF_SHARED | IRQF_TRIGGER_RISING,
                          "uartlite", port);
        if (ret)
@@ -277,9 +286,12 @@ static int ulite_startup(struct uart_port *port)

 static void ulite_shutdown(struct uart_port *port)
 {
+       struct uartlite_data *pdata = port->private_data;
+
        uart_out32(0, ULITE_CONTROL, port);
        uart_in32(ULITE_CONTROL, port); /* dummy */
        free_irq(port->irq, port);
+       clk_disable(pdata->clk);
 }

 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
@@ -370,6 +382,17 @@ static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
        return -EINVAL;
 }

+static void ulite_pm(struct uart_port *port, unsigned int state,
+                    unsigned int oldstate)
+{
+       struct uartlite_data *pdata = port->private_data;
+
+       if (!state)
+               clk_enable(pdata->clk);
+       else
+               clk_disable(pdata->clk);
+}
+
 #ifdef CONFIG_CONSOLE_POLL
 static int ulite_get_poll_char(struct uart_port *port)
 {
@@ -405,6 +428,7 @@ static const struct uart_ops ulite_ops = {
        .request_port   = ulite_request_port,
        .config_port    = ulite_config_port,
        .verify_port    = ulite_verify_port,
+       .pm             = ulite_pm,
 #ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = ulite_get_poll_char,
        .poll_put_char  = ulite_put_poll_char,
@@ -669,7 +693,6 @@ static int ulite_release(struct device *dev)
 /* ---------------------------------------------------------------------
  * Platform bus binding
  */
-
 #if defined(CONFIG_OF)
 /* Match table for of_platform binding */
 static const struct of_device_id ulite_of_match[] = {
@@ -684,7 +707,7 @@ static int ulite_probe(struct platform_device *pdev)
 {
        struct resource *res;
        struct uartlite_data *pdata;
-       int irq;
+       int irq, ret;
        int id = pdev->id;
 #ifdef CONFIG_OF
        const __be32 *prop;
@@ -706,11 +729,33 @@ static int ulite_probe(struct platform_device *pdev)
        if (irq <= 0)
                return -ENXIO;

+       pdata->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
+       if (IS_ERR(pdata->clk)) {
+               if (PTR_ERR(pdata->clk) != -ENOENT)
+                       return PTR_ERR(pdata->clk);
+
+               /*
+                * Clock framework support is optional, continue on
+                * anyways if we don't find a matching clock.
+                */
+               pdata->clk = NULL;
+       }
+
+       ret = clk_prepare(pdata->clk);
+       if (ret) {
+               dev_err(&pdev->dev, "Failed to prepare clock\n");
+               return ret;
+       }
+
        return ulite_assign(&pdev->dev, id, res->start, irq, pdata);
 }

 static int ulite_remove(struct platform_device *pdev)
 {
+       struct uart_port *port = dev_get_drvdata(&pdev->dev);
+       struct uartlite_data *pdata = port->private_data;
+
+       clk_disable_unprepare(pdata->clk);
        return ulite_release(&pdev->dev);
 }

--
2.7.4

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