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 Stevam <festevam@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxxx>
Cc: linux-serial@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Eduardo Valentin <edubezval@xxxxxxxxx>
---
drivers/tty/serial/imx.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index a03855d..494b182 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -217,6 +217,8 @@ struct imx_port {
unsigned int tx_bytes;
unsigned int dma_tx_nents;
wait_queue_head_t dma_wait;
+ unsigned int saved_reg[8];
+ bool context_saved;
};
struct imx_port_ucrs {
@@ -1803,6 +1805,36 @@ static struct uart_driver imx_reg = {
.cons = IMX_CONSOLE,
};
+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 + UBIR);
+ writel(sport->saved_reg[6], sport->port.membase + UBMR);
+ writel(sport->saved_reg[7], sport->port.membase + IMX21_UTS);
+ writel(sport->saved_reg[0], sport->port.membase + UCR1);
+ writel(sport->saved_reg[1] | 0x1, 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 + UBIR);
+ sport->saved_reg[6] = readl(sport->port.membase + UBMR);
+ sport->saved_reg[7] = 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;
@@ -1826,6 +1858,7 @@ static int serial_imx_suspend(struct device *dev)
{
struct imx_port *sport = dev_get_drvdata(dev);
+ serial_imx_save_context(sport);
/* enable wakeup from i.MX UART */
serial_imx_enable_wakeup(sport, true);
@@ -1841,6 +1874,7 @@ static int serial_imx_resume(struct device *dev)
/* disable wakeup from i.MX UART */
serial_imx_enable_wakeup(sport, false);
+ serial_imx_restore_context(sport);
uart_resume_port(&imx_reg, &sport->port);
return 0;
--
2.5.0
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