[PATCH v2 2/4] serial: sprd: Add power management for the Spreadtrum serial controller

[Baolin Wang]

From: Lanqing Liu <lanqing....@unisoc.com>

This patch adds power management for the Spreadtrum serial controller.

Signed-off-by: Lanqing Liu <lanqing....@unisoc.com>
Signed-off-by: Baolin Wang <baolin.w...@linaro.org>
---
 drivers/tty/serial/sprd_serial.c |   61 +++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 1891a45..8f45b66 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -100,10 +100,12 @@
 #define SPRD_IMSR_TX_FIFO_EMPTY        BIT(1)
 #define SPRD_IMSR_BREAK_DETECT BIT(7)
 #define SPRD_IMSR_TIMEOUT      BIT(13)
+#define SPRD_DEFAULT_SOURCE_CLK        26000000
 
 struct sprd_uart_port {
        struct uart_port port;
        char name[16];
+       struct clk *clk;
 };
 
 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
@@ -491,6 +493,22 @@ static int sprd_verify_port(struct uart_port *port, struct 
serial_struct *ser)
        return 0;
 }
 
+static void sprd_pm(struct uart_port *port, unsigned int state,
+               unsigned int oldstate)
+{
+       struct sprd_uart_port *sup =
+               container_of(port, struct sprd_uart_port, port);
+
+       switch (state) {
+       case UART_PM_STATE_ON:
+               clk_prepare_enable(sup->clk);
+               break;
+       case UART_PM_STATE_OFF:
+               clk_disable_unprepare(sup->clk);
+               break;
+       }
+}
+
 static const struct uart_ops serial_sprd_ops = {
        .tx_empty = sprd_tx_empty,
        .get_mctrl = sprd_get_mctrl,
@@ -507,6 +525,7 @@ static int sprd_verify_port(struct uart_port *port, struct 
serial_struct *ser)
        .request_port = sprd_request_port,
        .config_port = sprd_config_port,
        .verify_port = sprd_verify_port,
+       .pm = sprd_pm,
 };
 
 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
@@ -671,11 +690,45 @@ static int sprd_remove(struct platform_device *dev)
        return 0;
 }
 
+static int sprd_clk_init(struct uart_port *uport)
+{
+       struct clk *clk_uart, *clk_parent;
+       struct sprd_uart_port *u = sprd_port[uport->line];
+
+       clk_uart = devm_clk_get(uport->dev, "uart");
+       if (IS_ERR(clk_uart)) {
+               dev_warn(uport->dev, "uart%d can't get uart clock\n",
+                        uport->line);
+               clk_uart = NULL;
+       }
+
+       clk_parent = devm_clk_get(uport->dev, "source");
+       if (IS_ERR(clk_parent)) {
+               dev_warn(uport->dev, "uart%d can't get source clock\n",
+                        uport->line);
+               clk_parent = NULL;
+       }
+
+       if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
+               uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
+       else
+               uport->uartclk = clk_get_rate(clk_uart);
+
+       u->clk = devm_clk_get(uport->dev, "enable");
+       if (IS_ERR(u->clk)) {
+               if (PTR_ERR(u->clk) != -EPROBE_DEFER)
+                       dev_err(uport->dev, "uart%d can't get enable clock\n",
+                               uport->line);
+               return PTR_ERR(u->clk);
+       }
+
+       return 0;
+}
+
 static int sprd_probe(struct platform_device *pdev)
 {
        struct resource *res;
        struct uart_port *up;
-       struct clk *clk;
        int irq;
        int index;
        int ret;
@@ -704,9 +757,9 @@ static int sprd_probe(struct platform_device *pdev)
        up->ops = &serial_sprd_ops;
        up->flags = UPF_BOOT_AUTOCONF;
 
-       clk = devm_clk_get(&pdev->dev, NULL);
-       if (!IS_ERR_OR_NULL(clk))
-               up->uartclk = clk_get_rate(clk);
+       ret = sprd_clk_init(up);
+       if (ret)
+               return ret;
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        up->membase = devm_ioremap_resource(&pdev->dev, res);
-- 
1.7.9.5