serial: imx: save and restore context in the suspend path

This change teaches the imx serial driver to save its
context and restore it across suspend and resume path.
To do so, it introduces serial_imx_restore_context()
and serial_imx_save_context() functions. They use
a shadow set of registers to save key registers
and restore them accordingly. These functions can
be reused on other situations, when the device
context is lost.

Cc: Fabio Estevam <festevam@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 167dea1adf90083dce7a1aca8ab4280d46ead3b0..fe3d41cc841632134fd907b1fb7af08f0e9d6e81 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -217,6 +217,7 @@ struct imx_port {
        unsigned int            dma_tx_nents;
        wait_queue_head_t       dma_wait;
        unsigned int            saved_reg[10];
+       bool                    context_saved;
 };
 
 struct imx_port_ucrs {
@@ -1972,6 +1973,40 @@ static int serial_imx_remove(struct platform_device *pdev)
        return uart_remove_one_port(&imx_reg, &sport->port);
 }
 
+static void serial_imx_restore_context(struct imx_port *sport)
+{
+       if (!sport->context_saved)
+               return;
+
+       writel(sport->saved_reg[4], sport->port.membase + UFCR);
+       writel(sport->saved_reg[5], sport->port.membase + UESC);
+       writel(sport->saved_reg[6], sport->port.membase + UTIM);
+       writel(sport->saved_reg[7], sport->port.membase + UBIR);
+       writel(sport->saved_reg[8], sport->port.membase + UBMR);
+       writel(sport->saved_reg[9], sport->port.membase + IMX21_UTS);
+       writel(sport->saved_reg[0], sport->port.membase + UCR1);
+       writel(sport->saved_reg[1] | UCR2_SRST, sport->port.membase + UCR2);
+       writel(sport->saved_reg[2], sport->port.membase + UCR3);
+       writel(sport->saved_reg[3], sport->port.membase + UCR4);
+       sport->context_saved = false;
+}
+
+static void serial_imx_save_context(struct imx_port *sport)
+{
+       /* Save necessary regs */
+       sport->saved_reg[0] = readl(sport->port.membase + UCR1);
+       sport->saved_reg[1] = readl(sport->port.membase + UCR2);
+       sport->saved_reg[2] = readl(sport->port.membase + UCR3);
+       sport->saved_reg[3] = readl(sport->port.membase + UCR4);
+       sport->saved_reg[4] = readl(sport->port.membase + UFCR);
+       sport->saved_reg[5] = readl(sport->port.membase + UESC);
+       sport->saved_reg[6] = readl(sport->port.membase + UTIM);
+       sport->saved_reg[7] = readl(sport->port.membase + UBIR);
+       sport->saved_reg[8] = readl(sport->port.membase + UBMR);
+       sport->saved_reg[9] = readl(sport->port.membase + IMX21_UTS);
+       sport->context_saved = true;
+}
+
 static void serial_imx_enable_wakeup(struct imx_port *sport, bool on)
 {
        unsigned int val;
@@ -2001,17 +2036,7 @@ static int imx_serial_port_suspend_noirq(struct device *dev)
        if (ret)
                return ret;
 
-       /* Save necessary regs */
-       sport->saved_reg[0] = readl(sport->port.membase + UCR1);
-       sport->saved_reg[1] = readl(sport->port.membase + UCR2);
-       sport->saved_reg[2] = readl(sport->port.membase + UCR3);
-       sport->saved_reg[3] = readl(sport->port.membase + UCR4);
-       sport->saved_reg[4] = readl(sport->port.membase + UFCR);
-       sport->saved_reg[5] = readl(sport->port.membase + UESC);
-       sport->saved_reg[6] = readl(sport->port.membase + UTIM);
-       sport->saved_reg[7] = readl(sport->port.membase + UBIR);
-       sport->saved_reg[8] = readl(sport->port.membase + UBMR);
-       sport->saved_reg[9] = readl(sport->port.membase + IMX21_UTS);
+       serial_imx_save_context(sport);
 
        clk_disable(sport->clk_ipg);
 
@@ -2028,16 +2053,7 @@ static int imx_serial_port_resume_noirq(struct device *dev)
        if (ret)
                return ret;
 
-       writel(sport->saved_reg[4], sport->port.membase + UFCR);
-       writel(sport->saved_reg[5], sport->port.membase + UESC);
-       writel(sport->saved_reg[6], sport->port.membase + UTIM);
-       writel(sport->saved_reg[7], sport->port.membase + UBIR);
-       writel(sport->saved_reg[8], sport->port.membase + UBMR);
-       writel(sport->saved_reg[9], sport->port.membase + IMX21_UTS);
-       writel(sport->saved_reg[0], sport->port.membase + UCR1);
-       writel(sport->saved_reg[1] | UCR2_SRST, sport->port.membase + UCR2);
-       writel(sport->saved_reg[2], sport->port.membase + UCR3);
-       writel(sport->saved_reg[3], sport->port.membase + UCR4);
+       serial_imx_restore_context(sport);
 
        clk_disable(sport->clk_ipg);