serial: sprd: Add power management for the Spreadtrum serial controller

This patch adds power management for the Spreadtrum serial controller.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 57 insertions, 4 deletions

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 1891a45ac05d..8f45b6671c19 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 const struct uart_ops serial_sprd_ops = {
         .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);