[PATCH V3 3/3] GPIO: MIPS: lantiq: convert gpio-stp-xway to OF

[John Crispin]

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@xxxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
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@xxxxxxxxxxx>
+ *  Copyright (C) 2012 John Crispin <blogic@xxxxxxxxxxx>
  *
  */
 
 #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;
+
+	/* 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

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