From c868cbb7e5c6d3c74b8d38c7c356444f2c807c28 Mon Sep 17 00:00:00 2001
From: Eduardo Valentin <edubezval@gmail.com>
Date: Tue, 11 Aug 2015 10:21:23 -0700
Subject: 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 @@ 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);
 
-- 
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