Date:	Thu, 17 May 2012 12:38:30 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	John Crispin <blogic@...nwrt.org>
Cc:	linux-mips@...ux-mips.org, John Crispin <blogic@...nwrt.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 3/3] GPIO: MIPS: lantiq: convert gpio-stp-xway to OF

On Wed, 16 May 2012 22:49:54 +0200, John Crispin <blogic@...nwrt.org> wrote:
> Implements OF support and add code to load custom properties from the DT.
> 
> The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
> peripheral controller used to drive external shift register cascades. At most
> 3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
> to drive the 2 LSBs of the cascade automatically. Newer socs are also able to
> automatically drive some pins via the internal PHYs. The driver currently only
> supports output functionality. Patches for the input feature found on newer
> generations of the soc will be provided in a later series.
> 
> Signed-off-by: John Crispin <blogic@...nwrt.org>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: linux-kernel@...r.kernel.org

My comments on the other patch apply equally here and should be
addressed, but you can add my:

Acked-by: Grant Likely <grant.likely@...retlab.ca>

Oh! And documentation!  You must add documentation for both GPIO
controllers to Documentation/devicetree/bindings/gpio.  Don't merge
until the documentation is written and added to the patch.

> ---
> This patch is part of a series moving the mips/lantiq target to OF and clkdev
> support. The patch, once Acked, should go upstream via Ralf's MIPS tree.
> 
>  drivers/gpio/gpio-stp-xway.c |  332 ++++++++++++++++++++++++++++++------------
>  1 files changed, 240 insertions(+), 92 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-stp-xway.c b/drivers/gpio/gpio-stp-xway.c
> index d674f1b..9b53adf 100644
> --- a/drivers/gpio/gpio-stp-xway.c
> +++ b/drivers/gpio/gpio-stp-xway.c
> @@ -3,150 +3,298 @@
>   *  under the terms of the GNU General Public License version 2 as published
>   *  by the Free Software Foundation.
>   *
> - *  Copyright (C) 2007 John Crispin <blogic@...nwrt.org>
> + *  Copyright (C) 2012 John Crispin <blogic@...nwrt.org>
>   *
>   */
>  
>  #include <linux/slab.h>
>  #include <linux/init.h>
> -#include <linux/export.h>
> +#include <linux/module.h>
>  #include <linux/types.h>
> -#include <linux/platform_device.h>
> +#include <linux/of_platform.h>
>  #include <linux/mutex.h>
>  #include <linux/io.h>
> -#include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
>  
>  #include <lantiq_soc.h>
>  
> -#define LTQ_STP_CON0		0x00
> -#define LTQ_STP_CON1		0x04
> -#define LTQ_STP_CPU0		0x08
> -#define LTQ_STP_CPU1		0x0C
> -#define LTQ_STP_AR		0x10
> -
> -#define LTQ_STP_CON_SWU		(1 << 31)
> -#define LTQ_STP_2HZ		0
> -#define LTQ_STP_4HZ		(1 << 23)
> -#define LTQ_STP_8HZ		(2 << 23)
> -#define LTQ_STP_10HZ		(3 << 23)
> -#define LTQ_STP_SPEED_MASK	(0xf << 23)
> -#define LTQ_STP_UPD_FPI		(1 << 31)
> -#define LTQ_STP_UPD_MASK	(3 << 30)
> -#define LTQ_STP_ADSL_SRC	(3 << 24)
> -
> -#define LTQ_STP_GROUP0		(1 << 0)
> -
> -#define LTQ_STP_RISING		0
> -#define LTQ_STP_FALLING		(1 << 26)
> -#define LTQ_STP_EDGE_MASK	(1 << 26)
> -
> -#define ltq_stp_r32(reg)	__raw_readl(ltq_stp_membase + reg)
> -#define ltq_stp_w32(val, reg)	__raw_writel(val, ltq_stp_membase + reg)
> -#define ltq_stp_w32_mask(clear, set, reg) \
> -		ltq_w32((ltq_r32(ltq_stp_membase + reg) & ~(clear)) | (set), \
> -		ltq_stp_membase + (reg))
> -
> -static int ltq_stp_shadow = 0xffff;
> -static void __iomem *ltq_stp_membase;
> -
> -static void ltq_stp_set(struct gpio_chip *chip, unsigned offset, int value)
> +/*
> + * The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
> + * peripheral controller used to drive external shift register cascades. At most
> + * 3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
> + * to drive the 2 LSBs of the cascade automatically.
> + */
> +
> +/* control register 0 */
> +#define XWAY_STP_CON0		0x00
> +/* control register 1 */
> +#define XWAY_STP_CON1		0x04
> +/* data register 0 */
> +#define XWAY_STP_CPU0		0x08
> +/* data register 1 */
> +#define XWAY_STP_CPU1		0x0C
> +/* access register */
> +#define XWAY_STP_AR		0x10
> +
> +/* software or hardware update select bit */
> +#define XWAY_STP_CON_SWU	BIT(31)
> +
> +/* automatic update rates */
> +#define XWAY_STP_2HZ		0
> +#define XWAY_STP_4HZ		BIT(23)
> +#define XWAY_STP_8HZ		BIT(24)
> +#define XWAY_STP_10HZ		(BIT(24) | BIT(23))
> +#define XWAY_STP_SPEED_MASK	(0xf << 23)
> +
> +/* clock source for automatic update */
> +#define XWAY_STP_UPD_FPI	BIT(31)
> +#define XWAY_STP_UPD_MASK	(BIT(31) | BIT(30))
> +
> +/* let the adsl core drive the 2 LSBs */
> +#define XWAY_STP_ADSL_SHIFT	24
> +#define XWAY_STP_ADSL_MASK	0x3
> +
> +/* 2 groups of 3 bits can be driven by the phys */
> +#define XWAY_STP_PHY_MASK	0x3
> +#define XWAY_STP_PHY1_SHIFT	27
> +#define XWAY_STP_PHY2_SHIFT	15
> +
> +/* STP has 3 groups of 8 bits */
> +#define XWAY_STP_GROUP0		BIT(0)
> +#define XWAY_STP_GROUP1		BIT(1)
> +#define XWAY_STP_GROUP2		BIT(2)
> +#define XWAY_STP_GROUP_MASK	(0x7)
> +
> +/* Edge configuration bits */
> +#define XWAY_STP_FALLING	BIT(26)
> +#define XWAY_STP_EDGE_MASK	BIT(26)
> +
> +#define xway_stp_r32(m, reg)		__raw_readl(m + reg)
> +#define xway_stp_w32(m, val, reg)	__raw_writel(val, m + reg)
> +#define xway_stp_w32_mask(m, clear, set, reg) \
> +		ltq_w32((ltq_r32(m + reg) & ~(clear)) | (set), \
> +		m + reg)
> +
> +struct xway_stp {
> +	struct gpio_chip gc;
> +	void __iomem *virt;
> +	u32 edge;	/* rising or falling edge triggered shift register */
> +	u16 shadow;	/* shadow the shift registers state */
> +	u8 groups;	/* we can drive 1-3 groups of 8bit each */
> +	u8 dsl;		/* the 2 LSBs can be driven by the dsl core */
> +	u8 phy1;	/* 3 bits can be driven by phy1 */
> +	u8 phy2;	/* 3 bits can be driven by phy2 */
> +	u8 reserved;	/* mask out the hw driven bits in gpio_request */
> +};
> +
> +/*
> + * xway_stp_set - gpio_chip->set - set gpios.
> + * @gc:     Pointer to gpio_chip device structure.
> + * @gpio:   GPIO signal number.
> + * @val:    Value to be written to specified signal.
> + *
> + * Set the shadow value and call ltq_ebu_apply.
> + */
> +static void xway_stp_set(struct gpio_chip *gc, unsigned gpio, int val)
>  {
> -	if (value)
> -		ltq_stp_shadow |= (1 << offset);
> +	struct xway_stp *chip =
> +		container_of(gc, struct xway_stp, gc);
> +
> +	if (val)
> +		chip->shadow |= BIT(gpio);
>  	else
> -		ltq_stp_shadow &= ~(1 << offset);
> -	ltq_stp_w32(ltq_stp_shadow, LTQ_STP_CPU0);
> +		chip->shadow &= ~BIT(gpio);
> +	xway_stp_w32(chip->virt, chip->shadow, XWAY_STP_CPU0);
> +	xway_stp_w32_mask(chip->virt, 0, XWAY_STP_CON_SWU, XWAY_STP_CON0);
>  }
>  
> -static int ltq_stp_direction_output(struct gpio_chip *chip, unsigned offset,
> -	int value)
> +/*
> + * xway_stp_dir_out - gpio_chip->dir_out - set gpio direction.
> + * @gc:     Pointer to gpio_chip device structure.
> + * @gpio:   GPIO signal number.
> + * @val:    Value to be written to specified signal.
> + *
> + * Same as xway_stp_set, always returns 0.
> + */
> +static int xway_stp_dir_out(struct gpio_chip *gc, unsigned gpio, int val)
>  {
> -	ltq_stp_set(chip, offset, value);
> +	xway_stp_set(gc, gpio, val);
>  
>  	return 0;
>  }
>  
> -static struct gpio_chip ltq_stp_chip = {
> -	.label = "ltq_stp",
> -	.direction_output = ltq_stp_direction_output,
> -	.set = ltq_stp_set,
> -	.base = 48,
> -	.ngpio = 24,
> -	.can_sleep = 1,
> -	.owner = THIS_MODULE,
> -};
> +/*
> + * xway_stp_request - gpio_chip->request
> + * @gc:     Pointer to gpio_chip device structure.
> + * @gpio:   GPIO signal number.
> + *
> + * We mask out the HW driven pins
> + */
> +static int xway_stp_request(struct gpio_chip *gc, unsigned gpio)
> +{
> +	struct xway_stp *chip =
> +		container_of(gc, struct xway_stp, gc);
> +
> +	if ((gpio < 8) && (chip->reserved & BIT(gpio))) {
> +		dev_err(gc->dev, "GPIO %d is driven by hardware\n", gpio);
> +		return -ENODEV;
> +	}
>  
> -static int ltq_stp_hw_init(void)
> +	return 0;
> +}
> +
> +/*
> + * xway_stp_hw_init - Configure the STP unit and enable the clock gate
> + * @virt: pointer to the remapped register range
> + */
> +static int xway_stp_hw_init(struct xway_stp *chip)
>  {
>  	/* sane defaults */
> -	ltq_stp_w32(0, LTQ_STP_AR);
> -	ltq_stp_w32(0, LTQ_STP_CPU0);
> -	ltq_stp_w32(0, LTQ_STP_CPU1);
> -	ltq_stp_w32(LTQ_STP_CON_SWU, LTQ_STP_CON0);
> -	ltq_stp_w32(0, LTQ_STP_CON1);
> +	xway_stp_w32(chip->virt, 0, XWAY_STP_AR);
> +	xway_stp_w32(chip->virt, 0, XWAY_STP_CPU0);
> +	xway_stp_w32(chip->virt, 0, XWAY_STP_CPU1);
> +	xway_stp_w32(chip->virt, XWAY_STP_CON_SWU, XWAY_STP_CON0);
> +	xway_stp_w32(chip->virt, 0, XWAY_STP_CON1);
> +
> +	/* apply edge trigger settings for the shift register */
> +	xway_stp_w32_mask(chip->virt, XWAY_STP_EDGE_MASK,
> +				chip->edge, XWAY_STP_CON0);
>  
> -	/* rising or falling edge */
> -	ltq_stp_w32_mask(LTQ_STP_EDGE_MASK, LTQ_STP_FALLING, LTQ_STP_CON0);
> +	/* apply led group settings */
> +	xway_stp_w32_mask(chip->virt, XWAY_STP_GROUP_MASK,
> +				chip->groups, XWAY_STP_CON1);
>  
> -	/* per default stp 15-0 are set */
> -	ltq_stp_w32_mask(0, LTQ_STP_GROUP0, LTQ_STP_CON1);
> +	/* tell the hardware which pins are controlled by the dsl modem */
> +	xway_stp_w32_mask(chip->virt,
> +			XWAY_STP_ADSL_MASK << XWAY_STP_ADSL_SHIFT,
> +			chip->dsl << XWAY_STP_ADSL_SHIFT,
> +			XWAY_STP_CON0);
>  
> -	/* stp are update periodically by the FPI bus */
> -	ltq_stp_w32_mask(LTQ_STP_UPD_MASK, LTQ_STP_UPD_FPI, LTQ_STP_CON1);
> +	/* tell the hardware which pins are controlled by the phys */
> +	xway_stp_w32_mask(chip->virt,
> +			XWAY_STP_PHY_MASK << XWAY_STP_PHY1_SHIFT,
> +			chip->phy1 << XWAY_STP_PHY1_SHIFT,
> +			XWAY_STP_CON0);
> +	xway_stp_w32_mask(chip->virt,
> +			XWAY_STP_PHY_MASK << XWAY_STP_PHY2_SHIFT,
> +			chip->phy2 << XWAY_STP_PHY2_SHIFT,
> +			XWAY_STP_CON1);
>  
> -	/* set stp update speed */
> -	ltq_stp_w32_mask(LTQ_STP_SPEED_MASK, LTQ_STP_8HZ, LTQ_STP_CON1);
> +	/* mask out the hw driven bits in gpio_request */
> +	chip->reserved = (chip->phy2 << 5) | (chip->phy1 << 2) | chip->dsl;
>  
> -	/* tell the hardware that pin (led) 0 and 1 are controlled
> -	 *  by the dsl arc
> +	/*
> +	 * if we have pins that are driven by hw, we need to tell the stp what
> +	 * clock to use as a timer.
>  	 */
> -	ltq_stp_w32_mask(0, LTQ_STP_ADSL_SRC, LTQ_STP_CON0);
> +	if (chip->reserved)
> +		xway_stp_w32_mask(chip->virt, XWAY_STP_UPD_MASK,
> +			XWAY_STP_UPD_FPI, XWAY_STP_CON1);
>  
> -	ltq_pmu_enable(PMU_LED);
>  	return 0;
>  }
>  
> -static int __devinit ltq_stp_probe(struct platform_device *pdev)
> +static int __devinit xway_stp_probe(struct platform_device *pdev)
>  {
>  	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	const __be32 *shadow, *groups, *dsl, *phy;
> +	struct xway_stp *chip;
> +	struct clk *clk;
>  	int ret = 0;
>  
> -	if (!res)
> -		return -ENOENT;
> -	res = devm_request_mem_region(&pdev->dev, res->start,
> -		resource_size(res), dev_name(&pdev->dev));
>  	if (!res) {
> -		dev_err(&pdev->dev, "failed to request STP memory\n");
> -		return -EBUSY;
> +		dev_err(&pdev->dev, "failed to request STP resource\n");
> +		return -ENOENT;
>  	}
> -	ltq_stp_membase = devm_ioremap_nocache(&pdev->dev, res->start,
> -		resource_size(res));
> -	if (!ltq_stp_membase) {
> +
> +	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->virt = devm_request_and_ioremap(&pdev->dev, res);
> +	if (!chip->virt) {
>  		dev_err(&pdev->dev, "failed to remap STP memory\n");
>  		return -ENOMEM;
>  	}
> -	ret = gpiochip_add(&ltq_stp_chip);
> +	chip->gc.dev = &pdev->dev;
> +	chip->gc.label = "stp-xway";
> +	chip->gc.direction_output = xway_stp_dir_out;
> +	chip->gc.set = xway_stp_set;
> +	chip->gc.request = xway_stp_request;
> +	chip->gc.base = -1;
> +	chip->gc.owner = THIS_MODULE;
> +
> +	/* store the shadow value if one was passed by the devicetree */
> +	shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL);
> +	if (shadow)
> +		chip->shadow = *shadow;

be32_to_cpu

> +
> +	/* find out which gpio groups should be enabled */
> +	groups = of_get_property(pdev->dev.of_node, "lantiq,groups", NULL);
> +	if (groups)
> +		chip->groups = *groups & XWAY_STP_GROUP_MASK;
> +	else
> +		chip->groups = XWAY_STP_GROUP0;
> +	chip->gc.ngpio = fls(chip->groups) * 8;
> +
> +	/* find out which gpios are controlled by the dsl core */
> +	dsl = of_get_property(pdev->dev.of_node, "lantiq,dsl", NULL);
> +	if (dsl)
> +		chip->dsl = *dsl & XWAY_STP_ADSL_MASK;
> +
> +	/* find out which gpios are controlled by the phys */
> +	if (of_machine_is_compatible("lantiq,ar9") ||
> +			of_machine_is_compatible("lantiq,gr9") ||
> +			of_machine_is_compatible("lantiq,vr9")) {
> +		phy = of_get_property(pdev->dev.of_node, "lantiq,phy1", NULL);
> +		if (phy)
> +			chip->phy1 = *phy & XWAY_STP_PHY_MASK;
> +		phy = of_get_property(pdev->dev.of_node, "lantiq,phy2", NULL);
> +		if (phy)
> +			chip->phy2 = *phy & XWAY_STP_PHY_MASK;
> +	}
> +
> +	/* check which edge trigger we should use, default to a falling edge */
> +	if (!of_find_property(pdev->dev.of_node, "lantiq,rising", NULL))
> +		chip->edge = XWAY_STP_FALLING;
> +
> +	clk = clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "Failed to get clock\n");
> +		return PTR_ERR(clk);
> +	}
> +	clk_enable(clk);
> +
> +	ret = xway_stp_hw_init(chip);
>  	if (!ret)
> -		ret = ltq_stp_hw_init();
> +		ret = gpiochip_add(&chip->gc);
> +
> +	if (!ret)
> +		dev_info(&pdev->dev, "Init done\n");
>  
>  	return ret;
>  }
>  
> -static struct platform_driver ltq_stp_driver = {
> -	.probe = ltq_stp_probe,
> +static const struct of_device_id xway_stp_match[] = {
> +	{ .compatible = "lantiq,gpio-stp-xway" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, xway_stp_match);
> +
> +static struct platform_driver xway_stp_driver = {
> +	.probe = xway_stp_probe,
>  	.driver = {
> -		.name = "ltq_stp",
> +		.name = "gpio-stp-xway",
>  		.owner = THIS_MODULE,
> +		.of_match_table = xway_stp_match,
>  	},
>  };
>  
> -int __init ltq_stp_init(void)
> +int __init xway_stp_init(void)
>  {
> -	int ret = platform_driver_register(&ltq_stp_driver);
> -
> -	if (ret)
> -		pr_info("ltq_stp: error registering platfom driver");
> -	return ret;
> +	return platform_driver_register(&xway_stp_driver);
>  }
>  
> -postcore_initcall(ltq_stp_init);
> +subsys_initcall(xway_stp_init);
> -- 
> 1.7.9.1
> 

-- 
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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