[PATCH v3 0/2] tty: serial: Add mediatek UART driver

[PATCH v3 0/2] tty: serial: Add mediatek UART driver

[Matthias Brugger]

This patch set adds support for the UART found in Mediatek SoCs.
The chip is a changed version of a 8250 controller.
Especially it introduces a new register called highspeed. The value
in this register has to be set depending on the baudrate. The value
in the register influences the way the divisor has to be calculated.

The patch series is build against v3.16-rc1 and tested on mt6589. Should
work as well on mt6577 and mt6582.

Thanks,
Matthias

Changes for v3:
- use dev_warn instead of pr_warn
- use 8250_core function to update termios

Changes for v2:
- drop 8250_core capability extension for the chip
- encapsulate set_termios in the driver method

---

Matthias Brugger (2):
  tty: serial: 8250: Add Mediatek UART driver
  DTS: serial: Add bindings documention for the Mediatek UARTs

 .../devicetree/bindings/serial/mtk-uart.txt        |   19 ++
 drivers/tty/serial/8250/8250_mtk.c                 |  296 ++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig                    |    7 +
 drivers/tty/serial/8250/Makefile                   |    1 +
 4 files changed, 323 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/mtk-uart.txt
 create mode 100644 drivers/tty/serial/8250/8250_mtk.c

-- 
1.7.9.5

[PATCH v3 1/2] tty: serial: 8250: Add Mediatek UART driver

[Matthias Brugger]

This patch adds support for the UART block found on Mediatek SoCs.
The device has a highspeed register which influences the calcualtion of the
divisor. The chip lacks support for some baudrates. When requested, we set the
divisor to the next smaller baudrate and adjust the c_cflag accordingly.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
---
 drivers/tty/serial/8250/8250_mtk.c |  296 ++++++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig    |    7 +
 drivers/tty/serial/8250/Makefile   |    1 +
 3 files changed, 304 insertions(+)
 create mode 100644 drivers/tty/serial/8250/8250_mtk.c

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
new file mode 100644
index 0000000..d63080b
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -0,0 +1,296 @@
+/*
+ * Mediatek 8250 driver.
+ *
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Matthias Brugger <matthias.bgg@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_reg.h>
+
+#include "8250.h"
+
+#define UART_MTK_HIGHS		0x09	/* Highspeed register */
+#define UART_MTK_SAMPLE_COUNT	0x0a	/* Sample count register */
+#define UART_MTK_SAMPLE_POINT	0x0b	/* Sample point register */
+#define MTK_UART_RATE_FIX	0x0d	/* UART Rate Fix Register */
+
+struct mtk8250_data {
+	int			line;
+	struct clk		*clk;
+};
+
+static void
+mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
+			struct ktermios *old)
+{
+	unsigned long flags;
+	unsigned int baud, quot;
+
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+
+	serial8250_do_set_termios(port, termios, old);
+
+	/*
+	 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
+	 *
+	 * We need to recalcualte the quot register, as the claculation depends
+	 * on the vaule in the highspeed register.
+	 *
+	 * Some baudrates are not supported by the chip, so we use the next
+	 * lower rate supported and update termios c_flag.
+	 *
+	 * If highspeed register is set to 3, we need to specify sample count
+	 * and sample point to increase accuracy. If not, we reset the
+	 * registers to their default values.
+	 */
+	baud = uart_get_baud_rate(port, termios, old,
+				  port->uartclk / 16 / 0xffff,
+				  port->uartclk / 16);
+
+	if (baud <= 115200) {
+		serial_port_out(port, UART_MTK_HIGHS, 0x0);
+		quot = uart_get_divisor(port, baud);
+	} else if (baud <= 576000) {
+		serial_port_out(port, UART_MTK_HIGHS, 0x2);
+
+		/* Set to next lower baudrate supported */
+		if ((baud == 500000) || (baud == 576000))
+			baud = 460800;
+		quot = DIV_ROUND_CLOSEST(port->uartclk, 4 * baud);
+	} else {
+		serial_port_out(port, UART_MTK_HIGHS, 0x3);
+
+		/* Set to highest baudrate supported */
+		if (baud >= 1152000)
+			baud = 921600;
+		quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
+	}
+
+	/*
+	 * Ok, we're now changing the port state.  Do it with
+	 * interrupts disabled.
+	 */
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* set DLAB we have cval saved in up->lcr from the call to the core */
+	serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB);
+	serial_dl_write(up, quot);
+
+	/* reset DLAB */
+	serial_port_out(port, UART_LCR, up->lcr);
+
+	if (baud > 460800) {
+		unsigned int tmp;
+
+		tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
+		serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
+		serial_port_out(port, UART_MTK_SAMPLE_POINT,
+					(tmp - 2) >> 1);
+	} else {
+		serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
+		serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+	/* Don't rewrite B0 */
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+}
+
+static void
+mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
+{
+	if (!state)
+		pm_runtime_get_sync(port->dev);
+
+	serial8250_do_pm(port, state, old);
+
+	if (state)
+		pm_runtime_put_sync_suspend(port->dev);
+}
+
+static int mtk8250_probe_of(struct uart_port *p,
+			   struct mtk8250_data *data)
+{
+	int err;
+	struct device_node	*np = p->dev->of_node;
+
+	data->clk = of_clk_get(np, 0);
+	if (IS_ERR(data->clk)) {
+		dev_warn(p->dev, "Can't get timer clock\n");
+		return PTR_ERR(data->clk);
+	}
+
+	err = clk_prepare_enable(data->clk);
+	if (err) {
+		dev_warn(p->dev, "Can't prepare clock\n");
+		clk_put(data->clk);
+		return err;
+	}
+	p->uartclk = clk_get_rate(data->clk);
+
+	return 0;
+}
+
+static int mtk8250_probe(struct platform_device *pdev)
+{
+	struct uart_8250_port uart = {};
+	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	struct mtk8250_data *data;
+	int err;
+
+	if (!regs || !irq) {
+		dev_err(&pdev->dev, "no registers/irq defined\n");
+		return -EINVAL;
+	}
+
+	spin_lock_init(&uart.port.lock);
+	uart.port.mapbase = regs->start;
+	uart.port.irq = irq->start;
+	uart.port.pm = mtk8250_do_pm;
+	uart.port.type = PORT_16550;
+	uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
+	uart.port.dev = &pdev->dev;
+
+	uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
+					 resource_size(regs));
+	if (!uart.port.membase)
+		return -ENOMEM;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	uart.port.iotype = UPIO_MEM32;
+	uart.port.regshift = 2;
+	uart.port.private_data = data;
+	uart.port.set_termios = mtk8250_set_termios;
+
+	if (pdev->dev.of_node) {
+		err = mtk8250_probe_of(&uart.port, data);
+		if (err)
+			return err;
+	} else
+		return -ENODEV;
+
+	/* Disable Rate Fix function */
+	writel(0x0, uart.port.membase +
+			(MTK_UART_RATE_FIX << uart.port.regshift));
+
+	data->line = serial8250_register_8250_port(&uart);
+	if (data->line < 0)
+		return data->line;
+
+	platform_set_drvdata(pdev, data);
+
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	return 0;
+}
+
+static int mtk8250_remove(struct platform_device *pdev)
+{
+	struct mtk8250_data *data = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+
+	serial8250_unregister_port(data->line);
+	if (!IS_ERR(data->clk)) {
+		clk_disable_unprepare(data->clk);
+		clk_put(data->clk);
+	}
+
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mtk8250_suspend(struct device *dev)
+{
+	struct mtk8250_data *data = dev_get_drvdata(dev);
+
+	serial8250_suspend_port(data->line);
+
+	return 0;
+}
+
+static int mtk8250_resume(struct device *dev)
+{
+	struct mtk8250_data *data = dev_get_drvdata(dev);
+
+	serial8250_resume_port(data->line);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM_RUNTIME
+static int mtk8250_runtime_suspend(struct device *dev)
+{
+	struct mtk8250_data *data = dev_get_drvdata(dev);
+
+	if (!IS_ERR(data->clk))
+		clk_disable_unprepare(data->clk);
+
+	return 0;
+}
+
+static int mtk8250_runtime_resume(struct device *dev)
+{
+	struct mtk8250_data *data = dev_get_drvdata(dev);
+
+	if (!IS_ERR(data->clk))
+		clk_prepare_enable(data->clk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops mtk8250_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume)
+	SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume,
+				NULL)
+};
+
+static const struct of_device_id mtk8250_of_match[] = {
+	{ .compatible = "mediatek,mt6577-uart" },
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mtk8250_of_match);
+
+static struct platform_driver mtk8250_platform_driver = {
+	.driver = {
+		.name		= "mt6577-uart",
+		.owner		= THIS_MODULE,
+		.pm		= &mtk8250_pm_ops,
+		.of_match_table	= mtk8250_of_match,
+	},
+	.probe			= mtk8250_probe,
+	.remove			= mtk8250_remove,
+};
+module_platform_driver(mtk8250_platform_driver);
+
+MODULE_AUTHOR("Matthias Brugger");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Mediatek 8250 serial port driver");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 349ee59..fac34aa 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -298,3 +298,10 @@ config SERIAL_8250_RT288X
 	  If you have a Ralink RT288x/RT305x SoC based board and want to use the
 	  serial port, say Y to this option. The driver can handle up to 2 serial
 	  ports. If unsure, say N.
+
+config SERIAL_8250_MT6577
+	bool "Mediatek serial port support"
+	depends on SERIAL_8250 && ARCH_MEDIATEK
+	help
+	  If you have a Mediatek based board and want to use the
+	  serial port, say Y to this option. If unsure, say N.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 36d68d0..6dcb46b 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_SERIAL_8250_HUB6)		+= 8250_hub6.o
 obj-$(CONFIG_SERIAL_8250_FSL)		+= 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o
+obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
-- 
1.7.9.5

[PATCH v3 2/2] DTS: serial: Add bindings documention for the Mediatek UARTs

[Matthias Brugger]

This patch adds the devicetree documentation for the Mediatek UART.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
---
 .../devicetree/bindings/serial/mtk-uart.txt        |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/mtk-uart.txt

diff --git a/Documentation/devicetree/bindings/serial/mtk-uart.txt b/Documentation/devicetree/bindings/serial/mtk-uart.txt
new file mode 100644
index 0000000..2bf571e
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/mtk-uart.txt
@@ -0,0 +1,19 @@
+* Mediatek Universal Asynchronous Receiver/Transmitter (UART)
+
+- compatible: "mediatek,mt6577-uart"
+  Compatibility with mt6577, mt6589, mt6582
+
+- reg: The base address of the UART register bank.
+
+- interrupts: A single interrupt specifier.
+
+- clocks: Clock driving the hardware.
+
+Example:
+
+	uart0: serial@11006000 {
+		compatible = "mediatek,mt6577-uart";
+		reg = <0x11006000 0x400>;
+		interrupts = <GIC_SPI 51 IRQ_TYPE_LEVEL_LOW>;
+		clocks = <&uart_clk>;
+	};
-- 
1.7.9.5

Re: [PATCH v3 2/2] DTS: serial: Add bindings documention for the Mediatek UARTs

[Varka Bhadram]

On 08/08/2014 05:02 PM, Matthias Brugger wrote:
> This patch adds the devicetree documentation for the Mediatek UART.
>
> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> ---
>   .../devicetree/bindings/serial/mtk-uart.txt        |   19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/serial/mtk-uart.txt
>
> diff --git a/Documentation/devicetree/bindings/serial/mtk-uart.txt b/Documentation/devicetree/bindings/serial/mtk-uart.txt
> new file mode 100644
> index 0000000..2bf571e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/serial/mtk-uart.txt
> @@ -0,0 +1,19 @@
> +* Mediatek Universal Asynchronous Receiver/Transmitter (UART)
> +

Missing Required Properties:....?



-- 
Regards,
Varka Bhadram.

Re: [PATCH v3 1/2] tty: serial: 8250: Add Mediatek UART driver

[Varka Bhadram]

On 08/08/2014 05:02 PM, Matthias Brugger wrote:
> This patch adds support for the UART block found on Mediatek SoCs.
> The device has a highspeed register which influences the calcualtion of the
> divisor. The chip lacks support for some baudrates. When requested, we set the
> divisor to the next smaller baudrate and adjust the c_cflag accordingly.

(...)

> +static struct platform_driver mtk8250_platform_driver = {
> +	.driver = {
> +		.name		= "mt6577-uart",
> +		.owner		= THIS_MODULE,

We can remove this field. Its updated by module_platform_driver()

Thanks.

-- 
Regards,
Varka Bhadram.

Re: [PATCH v3 1/2] tty: serial: 8250: Add Mediatek UART driver

[Tobias Klauser]

On 2014-08-08 at 13:32:03 +0200, Matthias Brugger <matthias.bgg@gmail.com> wrote:
> This patch adds support for the UART block found on Mediatek SoCs.
> The device has a highspeed register which influences the calcualtion of the
> divisor. The chip lacks support for some baudrates. When requested, we set the
> divisor to the next smaller baudrate and adjust the c_cflag accordingly.
> 
> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> ---
>  drivers/tty/serial/8250/8250_mtk.c |  296 ++++++++++++++++++++++++++++++++++++
>  drivers/tty/serial/8250/Kconfig    |    7 +
>  drivers/tty/serial/8250/Makefile   |    1 +
>  3 files changed, 304 insertions(+)
>  create mode 100644 drivers/tty/serial/8250/8250_mtk.c
> 
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> new file mode 100644
> index 0000000..d63080b
> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -0,0 +1,296 @@

[...]

> +static int mtk8250_probe(struct platform_device *pdev)
> +{
> +	struct uart_8250_port uart = {};
> +	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> +	struct mtk8250_data *data;
> +	int err;
> +
> +	if (!regs || !irq) {
> +		dev_err(&pdev->dev, "no registers/irq defined\n");
> +		return -EINVAL;
> +	}
> +
> +	spin_lock_init(&uart.port.lock);
> +	uart.port.mapbase = regs->start;
> +	uart.port.irq = irq->start;
> +	uart.port.pm = mtk8250_do_pm;
> +	uart.port.type = PORT_16550;
> +	uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
> +	uart.port.dev = &pdev->dev;
> +
> +	uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
> +					 resource_size(regs));
> +	if (!uart.port.membase)
> +		return -ENOMEM;

You can use devm_ioremap_resource here and get rid of the check for
!regs above, since devm_ioremap_resource already does that.

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	...

	uart.port.membase = devm_ioremap_resource(&pdev->dev, regs);
	if (IS_ERR(uart.port.membase))
		return PTR_ERR(uart.port.membase);

> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;

I'd suggest to move this kzalloc and the ioremap before the uart.port
initialization part above, so you can error out early in case of any
failure.

> +
> +	uart.port.iotype = UPIO_MEM32;
> +	uart.port.regshift = 2;
> +	uart.port.private_data = data;
> +	uart.port.set_termios = mtk8250_set_termios;
> +
> +	if (pdev->dev.of_node) {
> +		err = mtk8250_probe_of(&uart.port, data);
> +		if (err)
> +			return err;
> +	} else
> +		return -ENODEV;

This could also be moved up, directly below devm_kzalloc.

> +
> +	/* Disable Rate Fix function */
> +	writel(0x0, uart.port.membase +
> +			(MTK_UART_RATE_FIX << uart.port.regshift));
> +
> +	data->line = serial8250_register_8250_port(&uart);
> +	if (data->line < 0)
> +		return data->line;
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +
> +	return 0;
> +}
> +
> +static int mtk8250_remove(struct platform_device *pdev)
> +{
> +	struct mtk8250_data *data = platform_get_drvdata(pdev);
> +
> +	pm_runtime_get_sync(&pdev->dev);
> +
> +	serial8250_unregister_port(data->line);
> +	if (!IS_ERR(data->clk)) {
> +		clk_disable_unprepare(data->clk);
> +		clk_put(data->clk);
> +	}
> +
> +	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int mtk8250_suspend(struct device *dev)
> +{
> +	struct mtk8250_data *data = dev_get_drvdata(dev);
> +
> +	serial8250_suspend_port(data->line);
> +
> +	return 0;
> +}
> +
> +static int mtk8250_resume(struct device *dev)
> +{
> +	struct mtk8250_data *data = dev_get_drvdata(dev);
> +
> +	serial8250_resume_port(data->line);
> +
> +	return 0;
> +}
> +#endif /* CONFIG_PM_SLEEP */
> +
> +#ifdef CONFIG_PM_RUNTIME
> +static int mtk8250_runtime_suspend(struct device *dev)
> +{
> +	struct mtk8250_data *data = dev_get_drvdata(dev);
> +
> +	if (!IS_ERR(data->clk))
> +		clk_disable_unprepare(data->clk);
> +
> +	return 0;
> +}
> +
> +static int mtk8250_runtime_resume(struct device *dev)
> +{
> +	struct mtk8250_data *data = dev_get_drvdata(dev);
> +
> +	if (!IS_ERR(data->clk))
> +		clk_prepare_enable(data->clk);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops mtk8250_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume)
> +	SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume,
> +				NULL)
> +};
> +
> +static const struct of_device_id mtk8250_of_match[] = {
> +	{ .compatible = "mediatek,mt6577-uart" },
> +	{ /* Sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mtk8250_of_match);
> +
> +static struct platform_driver mtk8250_platform_driver = {
> +	.driver = {
> +		.name		= "mt6577-uart",
> +		.owner		= THIS_MODULE,

This doesn't need to be set here,
module_platform_driver/platform_driver_register take care of setting it.

> +		.pm		= &mtk8250_pm_ops,
> +		.of_match_table	= mtk8250_of_match,
> +	},
> +	.probe			= mtk8250_probe,
> +	.remove			= mtk8250_remove,
> +};
> +module_platform_driver(mtk8250_platform_driver);
> +
> +MODULE_AUTHOR("Matthias Brugger");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Mediatek 8250 serial port driver");

Re: [PATCH v3 1/2] tty: serial: 8250: Add Mediatek UART driver

[Matthias Brugger]

2014-08-08 14:28 GMT+02:00 Tobias Klauser <tklauser-93Khv+1bN0NyDzI6CaY1VQ@public.gmane.org>:
> On 2014-08-08 at 13:32:03 +0200, Matthias Brugger <matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> This patch adds support for the UART block found on Mediatek SoCs.
>> The device has a highspeed register which influences the calcualtion of the
>> divisor. The chip lacks support for some baudrates. When requested, we set the
>> divisor to the next smaller baudrate and adjust the c_cflag accordingly.
>>
>> Signed-off-by: Matthias Brugger <matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  drivers/tty/serial/8250/8250_mtk.c |  296 ++++++++++++++++++++++++++++++++++++
>>  drivers/tty/serial/8250/Kconfig    |    7 +
>>  drivers/tty/serial/8250/Makefile   |    1 +
>>  3 files changed, 304 insertions(+)
>>  create mode 100644 drivers/tty/serial/8250/8250_mtk.c
>>
>> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
>> new file mode 100644
>> index 0000000..d63080b
>> --- /dev/null
>> +++ b/drivers/tty/serial/8250/8250_mtk.c
>> @@ -0,0 +1,296 @@
>
> [...]
>
>> +static int mtk8250_probe(struct platform_device *pdev)
>> +{
>> +     struct uart_8250_port uart = {};
>> +     struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>> +     struct mtk8250_data *data;
>> +     int err;
>> +
>> +     if (!regs || !irq) {
>> +             dev_err(&pdev->dev, "no registers/irq defined\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     spin_lock_init(&uart.port.lock);
>> +     uart.port.mapbase = regs->start;
>> +     uart.port.irq = irq->start;
>> +     uart.port.pm = mtk8250_do_pm;
>> +     uart.port.type = PORT_16550;
>> +     uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
>> +     uart.port.dev = &pdev->dev;
>> +
>> +     uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
>> +                                      resource_size(regs));
>> +     if (!uart.port.membase)
>> +             return -ENOMEM;
>
> You can use devm_ioremap_resource here and get rid of the check for
> !regs above, since devm_ioremap_resource already does that.
>
>         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>
>         ...
>
>         uart.port.membase = devm_ioremap_resource(&pdev->dev, regs);
>         if (IS_ERR(uart.port.membase))
>                 return PTR_ERR(uart.port.membase);
>

devm_ioremap_resource creates a busy resource region in the
iomem_resource. This leads the UART to silently fail.
I suppose that's why 8250_dw.c uses devm_ioremap instead of
devm_ioremap_resource. The 8250_dw has the same issue.

Thanks,
Matthias

>> +
>> +     data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> +     if (!data)
>> +             return -ENOMEM;
>
> I'd suggest to move this kzalloc and the ioremap before the uart.port
> initialization part above, so you can error out early in case of any
> failure.
>
>> +
>> +     uart.port.iotype = UPIO_MEM32;
>> +     uart.port.regshift = 2;
>> +     uart.port.private_data = data;
>> +     uart.port.set_termios = mtk8250_set_termios;
>> +
>> +     if (pdev->dev.of_node) {
>> +             err = mtk8250_probe_of(&uart.port, data);
>> +             if (err)
>> +                     return err;
>> +     } else
>> +             return -ENODEV;
>
> This could also be moved up, directly below devm_kzalloc.
>
>> +
>> +     /* Disable Rate Fix function */
>> +     writel(0x0, uart.port.membase +
>> +                     (MTK_UART_RATE_FIX << uart.port.regshift));
>> +
>> +     data->line = serial8250_register_8250_port(&uart);
>> +     if (data->line < 0)
>> +             return data->line;
>> +
>> +     platform_set_drvdata(pdev, data);
>> +
>> +     pm_runtime_set_active(&pdev->dev);
>> +     pm_runtime_enable(&pdev->dev);
>> +
>> +     return 0;
>> +}
>> +
>> +static int mtk8250_remove(struct platform_device *pdev)
>> +{
>> +     struct mtk8250_data *data = platform_get_drvdata(pdev);
>> +
>> +     pm_runtime_get_sync(&pdev->dev);
>> +
>> +     serial8250_unregister_port(data->line);
>> +     if (!IS_ERR(data->clk)) {
>> +             clk_disable_unprepare(data->clk);
>> +             clk_put(data->clk);
>> +     }
>> +
>> +     pm_runtime_disable(&pdev->dev);
>> +     pm_runtime_put_noidle(&pdev->dev);
>> +     return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int mtk8250_suspend(struct device *dev)
>> +{
>> +     struct mtk8250_data *data = dev_get_drvdata(dev);
>> +
>> +     serial8250_suspend_port(data->line);
>> +
>> +     return 0;
>> +}
>> +
>> +static int mtk8250_resume(struct device *dev)
>> +{
>> +     struct mtk8250_data *data = dev_get_drvdata(dev);
>> +
>> +     serial8250_resume_port(data->line);
>> +
>> +     return 0;
>> +}
>> +#endif /* CONFIG_PM_SLEEP */
>> +
>> +#ifdef CONFIG_PM_RUNTIME
>> +static int mtk8250_runtime_suspend(struct device *dev)
>> +{
>> +     struct mtk8250_data *data = dev_get_drvdata(dev);
>> +
>> +     if (!IS_ERR(data->clk))
>> +             clk_disable_unprepare(data->clk);
>> +
>> +     return 0;
>> +}
>> +
>> +static int mtk8250_runtime_resume(struct device *dev)
>> +{
>> +     struct mtk8250_data *data = dev_get_drvdata(dev);
>> +
>> +     if (!IS_ERR(data->clk))
>> +             clk_prepare_enable(data->clk);
>> +
>> +     return 0;
>> +}
>> +#endif
>> +
>> +static const struct dev_pm_ops mtk8250_pm_ops = {
>> +     SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume)
>> +     SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume,
>> +                             NULL)
>> +};
>> +
>> +static const struct of_device_id mtk8250_of_match[] = {
>> +     { .compatible = "mediatek,mt6577-uart" },
>> +     { /* Sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, mtk8250_of_match);
>> +
>> +static struct platform_driver mtk8250_platform_driver = {
>> +     .driver = {
>> +             .name           = "mt6577-uart",
>> +             .owner          = THIS_MODULE,
>
> This doesn't need to be set here,
> module_platform_driver/platform_driver_register take care of setting it.
>
>> +             .pm             = &mtk8250_pm_ops,
>> +             .of_match_table = mtk8250_of_match,
>> +     },
>> +     .probe                  = mtk8250_probe,
>> +     .remove                 = mtk8250_remove,
>> +};
>> +module_platform_driver(mtk8250_platform_driver);
>> +
>> +MODULE_AUTHOR("Matthias Brugger");
>> +MODULE_LICENSE("GPL");
>> +MODULE_DESCRIPTION("Mediatek 8250 serial port driver");



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Re: [PATCH v3 1/2] tty: serial: 8250: Add Mediatek UART driver

[Tobias Klauser]

On 2014-08-12 at 15:31:51 +0200, Matthias Brugger <matthias.bgg@gmail.com> wrote:
> 2014-08-08 14:28 GMT+02:00 Tobias Klauser <tklauser@distanz.ch>:
> > On 2014-08-08 at 13:32:03 +0200, Matthias Brugger <matthias.bgg@gmail.com> wrote:
> >> This patch adds support for the UART block found on Mediatek SoCs.
> >> The device has a highspeed register which influences the calcualtion of the
> >> divisor. The chip lacks support for some baudrates. When requested, we set the
> >> divisor to the next smaller baudrate and adjust the c_cflag accordingly.
> >>
> >> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> >> ---
> >>  drivers/tty/serial/8250/8250_mtk.c |  296 ++++++++++++++++++++++++++++++++++++
> >>  drivers/tty/serial/8250/Kconfig    |    7 +
> >>  drivers/tty/serial/8250/Makefile   |    1 +
> >>  3 files changed, 304 insertions(+)
> >>  create mode 100644 drivers/tty/serial/8250/8250_mtk.c
> >>
> >> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> >> new file mode 100644
> >> index 0000000..d63080b
> >> --- /dev/null
> >> +++ b/drivers/tty/serial/8250/8250_mtk.c
> >> @@ -0,0 +1,296 @@
> >
> > [...]
> >
> >> +static int mtk8250_probe(struct platform_device *pdev)
> >> +{
> >> +     struct uart_8250_port uart = {};
> >> +     struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >> +     struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> >> +     struct mtk8250_data *data;
> >> +     int err;
> >> +
> >> +     if (!regs || !irq) {
> >> +             dev_err(&pdev->dev, "no registers/irq defined\n");
> >> +             return -EINVAL;
> >> +     }
> >> +
> >> +     spin_lock_init(&uart.port.lock);
> >> +     uart.port.mapbase = regs->start;
> >> +     uart.port.irq = irq->start;
> >> +     uart.port.pm = mtk8250_do_pm;
> >> +     uart.port.type = PORT_16550;
> >> +     uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
> >> +     uart.port.dev = &pdev->dev;
> >> +
> >> +     uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
> >> +                                      resource_size(regs));
> >> +     if (!uart.port.membase)
> >> +             return -ENOMEM;
> >
> > You can use devm_ioremap_resource here and get rid of the check for
> > !regs above, since devm_ioremap_resource already does that.
> >
> >         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >
> >         ...
> >
> >         uart.port.membase = devm_ioremap_resource(&pdev->dev, regs);
> >         if (IS_ERR(uart.port.membase))
> >                 return PTR_ERR(uart.port.membase);
> >
> 
> devm_ioremap_resource creates a busy resource region in the
> iomem_resource. This leads the UART to silently fail.
> I suppose that's why 8250_dw.c uses devm_ioremap instead of
> devm_ioremap_resource. The 8250_dw has the same issue.

Ah yes, of course. Sorry about that.

Thanks
Tobias