[PATCH 0/3] serial: 8250_uniphier: bug fix and suspend/resume support

[PATCH 0/3] serial: 8250_uniphier: bug fix and suspend/resume support

[Masahiro Yamada]

1/3 is a bug-fix (the driver may unregister a different port)

2/3 and 3/3 add suspend/resume support.



Masahiro Yamada (3):
  serial: 8250_uniphier: fix serial port index in private data
  serial: 8250_uniphier: use CHAR register for canary to detect
    power-off
  serial: 8250_uniphier: add suspend/resume support

 drivers/tty/serial/8250/8250_uniphier.c | 63 ++++++++++++++++++++++++++++-----
 1 file changed, 54 insertions(+), 9 deletions(-)

-- 
2.7.4

[PATCH 1/3] serial: 8250_uniphier: fix serial port index in private data

[Masahiro Yamada]

serial8250_register_8250_port() may allocate a different port index
than requested.  The driver needs to remember the returned value of
serial8250_register_8250_port() for later use.  Otherwise, the .remove
hook may unregister a different port.

Fixes: 1a8d2903cb6a ("serial: 8250_uniphier: add UniPhier serial driver")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 drivers/tty/serial/8250/8250_uniphier.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 746680ebf90c..633ac378b7f2 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -169,7 +169,7 @@ static int uniphier_of_serial_setup(struct device *dev, struct uart_port *port,
 		dev_err(dev, "failed to get alias id\n");
 		return ret;
 	}
-	port->line = priv->line = ret;
+	port->line = ret;
 
 	/* Get clk rate through clk driver */
 	priv->clk = devm_clk_get(dev, NULL);
@@ -249,8 +249,8 @@ static int uniphier_uart_probe(struct platform_device *pdev)
 	up.dl_read = uniphier_serial_dl_read;
 	up.dl_write = uniphier_serial_dl_write;
 
-	ret = serial8250_register_8250_port(&up);
-	if (ret < 0) {
+	priv->line = serial8250_register_8250_port(&up);
+	if (priv->line < 0) {
 		dev_err(dev, "failed to register 8250 port\n");
 		clk_disable_unprepare(priv->clk);
 		return ret;
-- 
2.7.4

[PATCH 2/3] serial: 8250_uniphier: use CHAR register for canary to detect power-off

[Masahiro Yamada]

The 8250 core uses the SCR as a canary to discover if the console has
been powered-off.

This hardware does not have SCR at offset 7, but an unused register
CHAR at a different offset.  As long as the character interrupt is
disabled, the register access has no impact, so it is useful as an
alternative scratch register.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 drivers/tty/serial/8250/8250_uniphier.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 633ac378b7f2..97a45b798fcd 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -29,12 +29,13 @@
  *   - MMIO32 (regshift = 2)
  *   - FCR is not at 2, but 3
  *   - LCR and MCR are not at 3 and 4, they share 4
+ *   - No SCR (Instead, CHAR can be used as a scratch register)
  *   - Divisor latch at 9, no divisor latch access bit
  */
 
 #define UNIPHIER_UART_REGSHIFT		2
 
-/* bit[15:8] = CHAR (not used), bit[7:0] = FCR */
+/* bit[15:8] = CHAR, bit[7:0] = FCR */
 #define UNIPHIER_UART_CHAR_FCR		(3 << (UNIPHIER_UART_REGSHIFT))
 /* bit[15:8] = LCR, bit[7:0] = MCR */
 #define UNIPHIER_UART_LCR_MCR		(4 << (UNIPHIER_UART_REGSHIFT))
@@ -72,13 +73,18 @@ OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
 
 /*
  * The register map is slightly different from that of 8250.
- * IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
+ * IO callbacks must be overridden for correct access to FCR, LCR, MCR and SCR.
  */
 static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
 {
 	unsigned int valshift = 0;
 
 	switch (offset) {
+	case UART_SCR:
+		/* No SCR for this hardware.  Use CHAR as a scratch register */
+		valshift = 8;
+		offset = UNIPHIER_UART_CHAR_FCR;
+		break;
 	case UART_LCR:
 		valshift = 8;
 		/* fall through */
@@ -91,8 +97,8 @@ static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
 	}
 
 	/*
-	 * The return value must be masked with 0xff because LCR and MCR reside
-	 * in the same register that must be accessed by 32-bit write/read.
+	 * The return value must be masked with 0xff because some registers
+	 * share the same offset that must be accessed by 32-bit write/read.
 	 * 8 or 16 bit access to this hardware result in unexpected behavior.
 	 */
 	return (readl(p->membase + offset) >> valshift) & 0xff;
@@ -101,9 +107,13 @@ static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
 static void uniphier_serial_out(struct uart_port *p, int offset, int value)
 {
 	unsigned int valshift = 0;
-	bool normal = true;
+	bool normal = false;
 
 	switch (offset) {
+	case UART_SCR:
+		/* No SCR for this hardware.  Use CHAR as a scratch register */
+		valshift = 8;
+		/* fall through */
 	case UART_FCR:
 		offset = UNIPHIER_UART_CHAR_FCR;
 		break;
@@ -114,10 +124,10 @@ static void uniphier_serial_out(struct uart_port *p, int offset, int value)
 		/* fall through */
 	case UART_MCR:
 		offset = UNIPHIER_UART_LCR_MCR;
-		normal = false;
 		break;
 	default:
 		offset <<= UNIPHIER_UART_REGSHIFT;
+		normal = true;
 		break;
 	}
 
-- 
2.7.4

[PATCH 3/3] serial: 8250_uniphier: add suspend/resume support

[Masahiro Yamada]

Add suspend/resume support for UniPhier serial driver.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 drivers/tty/serial/8250/8250_uniphier.c | 35 +++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 97a45b798fcd..8a10b10e27aa 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -281,6 +281,40 @@ static int uniphier_uart_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused uniphier_uart_suspend(struct device *dev)
+{
+	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
+	struct uart_8250_port *up = serial8250_get_port(priv->line);
+
+	serial8250_suspend_port(priv->line);
+
+	if (!uart_console(&up->port) || console_suspend_enabled)
+		clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused uniphier_uart_resume(struct device *dev)
+{
+	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
+	struct uart_8250_port *up = serial8250_get_port(priv->line);
+	int ret;
+
+	if (!uart_console(&up->port) || console_suspend_enabled) {
+		ret = clk_prepare_enable(priv->clk);
+		if (ret)
+			return ret;
+	}
+
+	serial8250_resume_port(priv->line);
+
+	return 0;
+}
+
+static const struct dev_pm_ops uniphier_uart_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
+};
+
 static const struct of_device_id uniphier_uart_match[] = {
 	{ .compatible = "socionext,uniphier-uart" },
 	{ /* sentinel */ }
@@ -293,6 +327,7 @@ static struct platform_driver uniphier_uart_platform_driver = {
 	.driver = {
 		.name	= "uniphier-uart",
 		.of_match_table = uniphier_uart_match,
+		.pm = &uniphier_uart_pm_ops,
 	},
 };
 module_platform_driver(uniphier_uart_platform_driver);
-- 
2.7.4