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 167dea1..fe3d41c 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -217,6 +217,7 @@
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 @@
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 @@
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 @@
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);