ux500: uart0: fix glitch in the tx pin in tty_open

when tty port0 is opened a glitch is seen in the tx line
of uart0. This happens in __pl011_startup() when tx fifo
interrupt is provoked into asserting.
Now uart0 pins are enabled (alt function) only when init
is complete and turned back to gpio when closed.

ST-Ericsson Linux next: - 336280
ST-Ericsson ID: 334262
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: I809eac2ab8aea643dd304fb80256b291cce75b59
Signed-off-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/20831
Reviewed-by: QATEST
Reviewed-by: Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com>

2 files changed, 52 insertions, 4 deletions

diff --git a/arch/arm/mach-ux500/board-mop500-pins.c b/arch/arm/mach-ux500/board-mop500-pins.c
index 703cf038e6f..6716da9c578 100644
--- a/arch/arm/mach-ux500/board-mop500-pins.c
+++ b/arch/arm/mach-ux500/board-mop500-pins.c
@@ -93,10 +93,18 @@ static pin_cfg_t mop500_pins_common[] = {
 	GPIO207_MC4_DAT4	| PIN_INPUT_PULLUP,
 
 	/* UART */
-	GPIO0_U0_CTSn	| PIN_INPUT_PULLUP,
-	GPIO1_U0_RTSn	| PIN_OUTPUT_HIGH,
-	GPIO2_U0_RXD	| PIN_INPUT_PULLUP,
-	GPIO3_U0_TXD	| PIN_OUTPUT_HIGH,
+	/* uart-0 pins gpio configuration should be
+	 * kept intact to prevent glitch in tx line
+	 * when tty dev is opened. Later these pins
+	 * are configured to uart mop500_pins_uart0
+	 *
+	 * It will be replaced with uart configuration
+	 * once the issue is solved.
+	 */
+	GPIO0_GPIO   | PIN_INPUT_PULLUP,
+	GPIO1_GPIO   | PIN_OUTPUT_HIGH,
+	GPIO2_GPIO   | PIN_INPUT_PULLUP,
+	GPIO3_GPIO   | PIN_OUTPUT_LOW,
 
 	GPIO29_U2_RXD	| PIN_INPUT_PULLUP,
 	GPIO30_U2_TXD	| PIN_OUTPUT_HIGH,
@@ -230,6 +238,14 @@ static pin_cfg_t u9500_21_pins[] = {
 	GPIO4_U1_RXD    | PIN_INPUT_PULLUP,
 	GPIO5_U1_TXD    | PIN_OUTPUT_HIGH,
 };
+
+static UX500_PINS(mop500_pins_uart0,
+	GPIO0_U0_CTSn	| PIN_INPUT_PULLUP,
+	GPIO1_U0_RTSn	| PIN_OUTPUT_HIGH,
+	GPIO2_U0_RXD	| PIN_INPUT_PULLUP,
+	GPIO3_U0_TXD	| PIN_OUTPUT_HIGH,
+);
+
 /*
  * I2C
  */
@@ -315,6 +331,7 @@ static UX500_PINS(mop500_pins_ske,
 static struct ux500_pin_lookup mop500_pins[] = {
 	PIN_LOOKUP("mcde-dpi", &mop500_pins_mcde_dpi),
 	PIN_LOOKUP("mcde-tvout", &mop500_pins_mcde_tvout),
+	PIN_LOOKUP("uart0", &mop500_pins_uart0),
 	PIN_LOOKUP("nmk-i2c.0", &mop500_pins_i2c0),
 	PIN_LOOKUP("nmk-i2c.1", &mop500_pins_i2c1),
 	PIN_LOOKUP("nmk-i2c.2", &mop500_pins_i2c2),
diff --git a/arch/arm/mach-ux500/board-mop500.c b/arch/arm/mach-ux500/board-mop500.c
index 965bfc6921f..5e059f9c2bf 100644
--- a/arch/arm/mach-ux500/board-mop500.c
+++ b/arch/arm/mach-ux500/board-mop500.c
@@ -1198,6 +1198,7 @@ static struct wlan1200_platform_data hrefv50_plat_data = {
 
 #define PRCC_K_SOFTRST_SET	0x18
 #define PRCC_K_SOFTRST_CLEAR	0x1C
+static struct ux500_pins *uart0_pins;
 static void ux500_pl011_reset(void)
 {
 	void __iomem *prcc_rst_set, *prcc_rst_clr;
@@ -1216,7 +1217,37 @@ static void ux500_pl011_reset(void)
 	udelay(1);
 }
 
+static void ux500_pl011_init(void)
+{
+	int ret;
+
+	if (!uart0_pins) {
+		uart0_pins = ux500_pins_get("uart0");
+		if (!uart0_pins) {
+			pr_err("pl011: uart0 pins_get failed\n");
+			return;
+		}
+	}
+
+	ret = ux500_pins_enable(uart0_pins);
+	if (ret)
+		pr_err("pl011: uart0 pins_enable failed\n");
+}
+
+static void ux500_pl011_exit(void)
+{
+	int ret;
+
+	if (uart0_pins) {
+		ret = ux500_pins_disable(uart0_pins);
+		if (ret)
+			pr_err("pl011: uart0 pins_disable failed\n");
+	}
+}
+
 static struct uart_amba_plat_data ux500_pl011_pdata = {
+	.init = ux500_pl011_init,
+	.exit = ux500_pl011_exit,
 	.reset = ux500_pl011_reset,
 };