Message-ID: <20141214203759.GA36053@dtor-ws>
Date:	Sun, 14 Dec 2014 12:37:59 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	VishnuPatekar <vishnupatekar0510@...il.com>
Cc:	linux-input@...r.kernel.org, maxime.ripard@...e-electrons.com,
	hdegoede@...hat.com, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux@....linux.org.uk, grant.likely@...aro.org,
	benh@...nel.crashing.org, msalter@...hat.com, ralf@...ux-mips.org,
	jdelvare@...e.de
Subject: Re: [PATCHv3 2/5] ARM:sunxi:drivers:input Add support for A10/A20 PS2

Hi Vishnu,

On Fri, Dec 12, 2014 at 11:55:45PM +0530, VishnuPatekar wrote:
> 
> Signed-off-by: VishnuPatekar <vishnupatekar0510@...il.com>
> ---
>  drivers/input/serio/Kconfig     |   11 ++
>  drivers/input/serio/Makefile    |    1 +
>  drivers/input/serio/sun4i-ps2.c |  362 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 374 insertions(+)
>  create mode 100644 drivers/input/serio/sun4i-ps2.c
> 
> diff --git a/drivers/input/serio/Kconfig b/drivers/input/serio/Kconfig
> index bc2d474..964afc5 100644
> --- a/drivers/input/serio/Kconfig
> +++ b/drivers/input/serio/Kconfig
> @@ -281,4 +281,15 @@ config HYPERV_KEYBOARD
>  	  To compile this driver as a module, choose M here: the module will
>  	  be called hyperv_keyboard.
>  
> +config SERIO_SUN4I_PS2
> +	tristate "Allwinner A10 PS/2 controller support"
> +	default n
> +	depends on ARCH_SUNXI || COMPILE_TEST
> +	help
> +	  This selects support for the PS/2 Host Controller on
> +	  Allwinner A10.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called sun4i-ps2.
> +
>  endif
> diff --git a/drivers/input/serio/Makefile b/drivers/input/serio/Makefile
> index 815d874..c600089 100644
> --- a/drivers/input/serio/Makefile
> +++ b/drivers/input/serio/Makefile
> @@ -29,3 +29,4 @@ obj-$(CONFIG_SERIO_ARC_PS2)	+= arc_ps2.o
>  obj-$(CONFIG_SERIO_APBPS2)	+= apbps2.o
>  obj-$(CONFIG_SERIO_OLPC_APSP)	+= olpc_apsp.o
>  obj-$(CONFIG_HYPERV_KEYBOARD)	+= hyperv-keyboard.o
> +obj-$(CONFIG_SERIO_SUN4I_PS2)	+= sun4i-ps2.o
> diff --git a/drivers/input/serio/sun4i-ps2.c b/drivers/input/serio/sun4i-ps2.c
> new file mode 100644
> index 0000000..e6d22ae
> --- /dev/null
> +++ b/drivers/input/serio/sun4i-ps2.c
> @@ -0,0 +1,362 @@
> +/*
> + *	Driver for Allwinner A10 PS2 host controller
> + *
> + *	Author: Vishnu Patekar <vishnupatekar0510@...il.com>
> + *		Aaron.maoye <leafy.myeh@...bietech.com>
> + *
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/serio.h>
> +#include <linux/interrupt.h>
> +#include <linux/errno.h>
> +#include <linux/slab.h>
> +#include <linux/list.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +
> +#define DRIVER_NAME		"sun4i-ps2"
> +
> +/* register offset definitions */
> +#define PS2_REG_GCTL		(0x00)	/*  PS2 Module Global Control Reg */
> +#define PS2_REG_DATA		(0x04)  /*  PS2 Module Data Reg		*/
> +#define PS2_REG_LCTL		(0x08)	/*  PS2 Module Line Control Reg */
> +#define PS2_REG_LSTS		(0x0C)  /*  PS2 Module Line Status Reg	*/
> +#define PS2_REG_FCTL		(0x10)	/*  PS2 Module FIFO Control Reg */
> +#define PS2_REG_FSTS		(0x14)	/*  PS2 Module FIFO Status Reg	*/
> +#define PS2_REG_CLKDR		(0x18)	/*  PS2 Module Clock Divider Reg*/

You do not need parenthesis around simple constants.

> +
> +/*  PS2 GLOBAL CONTROL REGISTER PS2_GCTL */
> +#define PS2_GCTL_INTFLAG	BIT(4)
> +#define PS2_GCTL_INTEN		BIT(3)
> +#define PS2_GCTL_RESET		BIT(2)
> +#define PS2_GCTL_MASTER		BIT(1)
> +#define PS2_GCTL_BUSEN		BIT(0)
> +
> +/* PS2 LINE CONTROL REGISTER */
> +#define PS2_LCTL_NOACK		BIT(18)
> +#define PS2_LCTL_TXDTOEN	BIT(8)
> +#define PS2_LCTL_STOPERREN	BIT(3)
> +#define PS2_LCTL_ACKERREN	BIT(2)
> +#define PS2_LCTL_PARERREN	BIT(1)
> +#define PS2_LCTL_RXDTOEN	BIT(0)
> +
> +/* PS2 LINE STATUS REGISTER */
> +#define PS2_LSTS_TXTDO		BIT(8)
> +#define PS2_LSTS_STOPERR	BIT(3)
> +#define PS2_LSTS_ACKERR		BIT(2)
> +#define PS2_LSTS_PARERR		BIT(1)
> +#define PS2_LSTS_RXTDO		BIT(0)
> +
> +#define PS2_LINE_ERROR_BIT \
> +	(PS2_LSTS_TXTDO | PS2_LSTS_STOPERR | PS2_LSTS_ACKERR | \
> +	PS2_LSTS_PARERR | PS2_LSTS_RXTDO)
> +
> +/* PS2 FIFO CONTROL REGISTER */
> +#define PS2_FCTL_TXRST		BIT(17)
> +#define PS2_FCTL_RXRST		BIT(16)
> +#define PS2_FCTL_TXUFIEN	BIT(10)
> +#define PS2_FCTL_TXOFIEN	BIT(9)
> +#define PS2_FCTL_TXRDYIEN	BIT(8)
> +#define PS2_FCTL_RXUFIEN	BIT(2)
> +#define PS2_FCTL_RXOFIEN	BIT(1)
> +#define PS2_FCTL_RXRDYIEN	BIT(0)
> +
> +/* PS2 FIFO STATUS REGISTER */
> +#define PS2_FSTS_TXUF		BIT(10)
> +#define PS2_FSTS_TXOF		BIT(9)
> +#define PS2_FSTS_TXRDY		BIT(8)
> +#define PS2_FSTS_RXUF		BIT(2)
> +#define PS2_FSTS_RXOF		BIT(1)
> +#define PS2_FSTS_RXRDY		BIT(0)
> +
> +#define PS2_FIFO_ERROR_BIT \
> +	(PS2_FSTS_TXUF | PS2_FSTS_TXOF | PS2_FSTS_RXUF | PS2_FSTS_RXOF)
> +
> +#define PS2_SAMPLE_CLK		(1000000)
> +#define PS2_SCLK		(125000)
> +
> +struct sun4i_ps2data {
> +	struct serio *serio;
> +	struct device *dev;
> +
> +	/* IO mapping base */
> +	void __iomem	*reg_base;
> +
> +	/* clock management */
> +	struct clk	*clk;
> +
> +	/* irq */
> +	spinlock_t	lock;
> +	int		irq;
> +};
> +
> +/*********************/
> +/* Interrupt handler */
> +/*********************/
> +static irqreturn_t sun4i_ps2_interrupt(int irq, void *dev_id)
> +{
> +	struct sun4i_ps2data *drvdata = dev_id;
> +	u32 intr_status;
> +	u32 fifo_status;
> +	unsigned char byte;
> +	u32 rval;
> +	u32 error = 0;
> +
> +	spin_lock(&drvdata->lock);
> +
> +	/* Get the PS/2 interrupts and clear them */
> +	intr_status  = readl(drvdata->reg_base + PS2_REG_LSTS);
> +	fifo_status  = readl(drvdata->reg_base + PS2_REG_FSTS);
> +
> +	/*Check Line Status Register*/
> +	if (intr_status & PS2_LINE_ERROR_BIT) {
> +		if (intr_status & PS2_LSTS_STOPERR)
> +			dev_info(drvdata->dev, "PS/2 Stop Bit Error!");

The stop bit error is I believe should be reported to consumers as
SSERIO_FRAME, receive timeout as SERIO_TIMEOUT and parity as
SERIO_PARITY.

> +		if (intr_status & PS2_LSTS_ACKERR)
> +			dev_info(drvdata->dev, "PS/2 Acknowledge Error!\n");

When is this error signalled?

> +		if (intr_status & PS2_LSTS_PARERR)
> +			dev_info(drvdata->dev, "PS/2 Parity Error!\n");
> +		if (intr_status & PS2_LSTS_TXTDO)
> +			dev_info(drvdata->dev, "PS/2 Transmit Data Timeout!\n");

Should not you check this status in serio_write() instead of here?

> +		if (intr_status & PS2_LSTS_RXTDO)
> +			dev_info(drvdata->dev, "PS/2 Receive Data Timeout!\n");
> +
> +		/*reset PS/2 controller*/
> +		rval = readl(drvdata->reg_base + PS2_REG_GCTL);
> +		writel(rval | PS2_GCTL_RESET, drvdata->reg_base + PS2_REG_GCTL);

Why do we need to reset controller in case of, let's say, parity glitch?

> +
> +		rval = PS2_LSTS_TXTDO | PS2_LSTS_STOPERR | PS2_LSTS_ACKERR |
> +			PS2_LSTS_PARERR | PS2_LSTS_RXTDO;
> +		writel(rval, drvdata->reg_base + PS2_REG_LSTS);
> +		error = 1;
> +	}
> +
> +	/*Check FIFO Status Register*/
> +	if (fifo_status & PS2_FIFO_ERROR_BIT) {
> +		if (fifo_status & PS2_FSTS_TXUF)
> +			dev_info(drvdata->dev, "PS/2 Tx FIFO Underflow!\n");
> +		if (fifo_status & PS2_FSTS_TXOF)
> +			dev_info(drvdata->dev, "PS/2 Tx FIFO Overflow!\n");
> +		if (fifo_status & PS2_FSTS_RXUF)
> +			dev_info(drvdata->dev, "PS/2 Rx FIFO Underflow!\n");
> +		if (fifo_status & PS2_FSTS_RXOF)
> +			dev_info(drvdata->dev, "PS/2 Rx FIFO Overflow!\n");
> +		/*reset PS/2 controller*/
> +		writel(readl(drvdata->reg_base + PS2_REG_GCTL) | PS2_GCTL_RESET,
> +			drvdata->reg_base + PS2_REG_GCTL);

Again, we do we need to reset controller? Does it stop receiving data
after RX overflow condition?

> +
> +		rval = PS2_FSTS_TXUF | PS2_FSTS_TXOF | PS2_FSTS_TXRDY |
> +			PS2_FSTS_RXUF | PS2_FSTS_RXOF | PS2_FSTS_RXRDY;
> +		writel(rval, drvdata->reg_base + PS2_REG_FSTS);
> +		error = 1;
> +	}
> +
> +	rval = (fifo_status >> 16) & 0x3;
> +	while (!error && rval--) {
> +		byte = readl(drvdata->reg_base + PS2_REG_DATA) & 0xff;
> +		serio_interrupt(drvdata->serio, byte, 0);
> +	}
> +
> +	writel(intr_status, drvdata->reg_base + PS2_REG_LSTS);
> +	writel(fifo_status, drvdata->reg_base + PS2_REG_FSTS);
> +
> +	spin_unlock(&drvdata->lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +
> +static int sun4i_ps2_open(struct serio *pserio)
> +{
> +	struct sun4i_ps2data *drvdata = pserio->port_data;
> +	u32 src_clk = 0;
> +	u32 clk_scdf;
> +	u32 clk_pcdf;
> +	u32 rval;
> +	unsigned long flags;
> +
> +	/*Set Line Control And Enable Interrupt*/
> +	rval = PS2_LCTL_TXDTOEN | PS2_LCTL_STOPERREN | PS2_LCTL_ACKERREN
> +		| PS2_LCTL_PARERREN | PS2_LCTL_RXDTOEN;
> +	writel(rval, drvdata->reg_base + PS2_REG_LCTL);
> +
> +	/*Reset FIFO*/
> +	rval = PS2_FCTL_TXRST | PS2_FCTL_RXRST | PS2_FCTL_TXUFIEN
> +		| PS2_FCTL_TXOFIEN | PS2_FCTL_RXUFIEN
> +		| PS2_FCTL_RXOFIEN | PS2_FCTL_RXRDYIEN;
> +
> +	writel(rval, drvdata->reg_base + PS2_REG_FCTL);
> +
> +	src_clk = clk_get_rate(drvdata->clk);
> +	/*Set Clock Divider Register*/
> +	clk_scdf = DIV_ROUND_UP(src_clk, PS2_SAMPLE_CLK) - 1;
> +	clk_pcdf = DIV_ROUND_UP(PS2_SAMPLE_CLK, PS2_SCLK) - 1;
> +	rval = (clk_scdf<<8) | clk_pcdf;
> +	writel(rval, drvdata->reg_base + PS2_REG_CLKDR);
> +
> +
> +	/*Set Global Control Register*/
> +	rval = PS2_GCTL_RESET | PS2_GCTL_INTEN | PS2_GCTL_MASTER
> +		| PS2_GCTL_BUSEN;
> +
> +	spin_lock_irqsave(&drvdata->lock, flags);
> +	writel(rval, drvdata->reg_base + PS2_REG_GCTL);
> +	spin_unlock_irqrestore(&drvdata->lock, flags);
> +
> +	return 0;
> +}
> +
> +static void sun4i_ps2_close(struct serio *pserio)
> +{
> +	struct sun4i_ps2data *drvdata = pserio->port_data;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&drvdata->lock, flags);
> +	/* Disable the PS2 interrupts */
> +	writel(0, drvdata->reg_base + PS2_REG_GCTL);
> +	spin_unlock_irqrestore(&drvdata->lock, flags);


I think you want to add synchronize_irq() here to make sure pending
interrupt handler runs to completion before you return.

> +}
> +
> +static int sun4i_ps2_write(struct serio *pserio, unsigned char val)
> +{
> +	unsigned long expire = jiffies + msecs_to_jiffies(10000);
> +	struct sun4i_ps2data *drvdata;
> +
> +	drvdata = (struct sun4i_ps2data *)pserio->port_data;
> +
> +	do {
> +		if (readl(drvdata->reg_base + PS2_REG_FSTS) & PS2_FSTS_TXRDY) {
> +			writel(val, drvdata->reg_base + PS2_REG_DATA);
> +			return 0;
> +		}
> +	} while (time_before(jiffies, expire));
> +
> +	return 0;
> +}
> +
> +static int sun4i_ps2_probe(struct platform_device *pdev)
> +{
> +	struct resource *res; /* IO mem resources */
> +	struct sun4i_ps2data *drvdata;
> +	struct serio *serio;
> +	struct device *dev = &pdev->dev;
> +	unsigned int irq;
> +	int error;
> +
> +	drvdata = devm_kzalloc(dev, sizeof(struct sun4i_ps2data), GFP_KERNEL);
> +	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
> +	if (!drvdata || !serio) {
> +		error = -ENOMEM;
> +		goto err_free_mem;
> +	}
> +
> +	spin_lock_init(&drvdata->lock);
> +
> +	/* IO */
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	drvdata->reg_base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(drvdata->reg_base)) {
> +		dev_err(dev, "failed to map registers\n");
> +		error = PTR_ERR(drvdata->reg_base);
> +		goto err_free_mem;
> +	}
> +
> +	drvdata->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(drvdata->clk)) {
> +		error = PTR_ERR(drvdata->clk);
> +		dev_err(dev, "couldn't get clock %d\n", error);
> +		goto err_free_mem;
> +	}
> +
> +	error = clk_prepare_enable(drvdata->clk);
> +	if (error) {
> +		dev_err(dev, "failed to enable clock %d\n", error);
> +		goto err_free_mem;
> +	}
> +

I think you should explicitly prohibit the device generating interrupts
by writing to PS2_ERG_CTRL here.

> +	serio->id.type = SERIO_8042;
> +	serio->write = sun4i_ps2_write;
> +	serio->open = sun4i_ps2_open;
> +	serio->close = sun4i_ps2_close;
> +	serio->port_data = drvdata;
> +	serio->dev.parent = dev;
> +	strlcpy(serio->name, dev_name(dev), sizeof(serio->name));
> +	strlcpy(serio->phys, dev_name(dev), sizeof(serio->phys));
> +
> +	/* Get IRQ for the device */
> +	irq = platform_get_irq(pdev, 0);
> +	if (!irq) {
> +		dev_err(dev, "no IRQ found\n");
> +		error = -ENXIO;
> +		goto error_disable_clk;
> +	}
> +
> +	drvdata->irq = irq;
> +	drvdata->serio = serio;
> +	drvdata->dev = dev;
> +	error = devm_request_threaded_irq(dev, drvdata->irq,
> +		sun4i_ps2_interrupt, NULL, 0, DRIVER_NAME, drvdata);
> +
> +	if (error) {
> +		dev_err(drvdata->dev, "Interrupt alloc failed %d:error:%d\n",
> +			drvdata->irq, error);
> +		goto error_disable_clk;
> +	}
> +
> +	serio_register_port(serio);
> +	platform_set_drvdata(pdev, drvdata);
> +
> +	return 0;	/* success */
> +
> +error_disable_clk:
> +	clk_disable_unprepare(drvdata->clk);
> +
> +err_free_mem:
> +	kfree(serio);
> +	return error;
> +}
> +
> +static int sun4i_ps2_remove(struct platform_device *pdev)
> +{
> +	struct sun4i_ps2data *drvdata = platform_get_drvdata(pdev);
> +
> +	serio_unregister_port(drvdata->serio);
> +	disable_irq(drvdata->irq);

I do not think you need to disable irq here - serio_close will make sure
that the device does not generate interrupts.

> +
> +	if (!IS_ERR(drvdata->clk))
> +		clk_disable_unprepare(drvdata->clk);
> +	kfree(drvdata->serio);
> +
> +	return 0;
> +}
> +
> +/* Match table for of_platform binding */
> +static const struct of_device_id sun4i_ps2_match[] = {
> +	{ .compatible = "allwinner,sun4i-a10-ps2", },
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(of, sun4i_ps2_match);
> +
> +/*platform driver structure*/

I do not think we should keep the obvious comments like this one.

> +static struct platform_driver sun4i_ps2_driver = {
> +	.probe		= sun4i_ps2_probe,
> +	.remove		= sun4i_ps2_remove,
> +	.driver = {
> +		.name = DRIVER_NAME,
> +		.of_match_table = sun4i_ps2_match,
> +	},
> +};
> +module_platform_driver(sun4i_ps2_driver);
> +
> +MODULE_AUTHOR("Vishnu Patekar <vishnupatekar0510@...il.com>");
> +MODULE_AUTHOR("Aaron.maoye <leafy.myeh@...bietech.com>");
> +MODULE_DESCRIPTION("Allwinner A10/Sun4i PS/2 driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 1.7.9.5
> 

Thanks.

-- 
Dmitry
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