[ARM] S3C: GPIO PM core GPIOlib integration

Move the GPIO suspend/resume support inline with the gpiolib support
so that it will work with both the S3C24XX and S3C64XX series.

The s3c_gpio_chip is extended to have a pm callback and a save block
to keep the state of the GPIO over suspend, and the code from the
s3c24xx implementation is added to a new common file.

The suspend process now uses the list of registered chips to go through
saving and restoring each one as appropriate, using the pm callback to
select the appropriate routine depending on the type of control register
present.

This change also means that any additional GPIO added should not require
changes to the PM.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

4 files changed, 421 insertions, 1 deletions

diff --git a/arch/arm/plat-s3c/Makefile b/arch/arm/plat-s3c/Makefile
index aa995a4..bfc8f53 100644
--- a/arch/arm/plat-s3c/Makefile
+++ b/arch/arm/plat-s3c/Makefile
@@ -21,6 +21,7 @@ obj-y				+= gpio-config.o
 # PM support
 
 obj-$(CONFIG_PM)		+= pm.o
+obj-$(CONFIG_PM)		+= pm-gpio.o
 obj-$(CONFIG_S3C2410_PM_CHECK)	+= pm-check.o
 
 # devices
diff --git a/arch/arm/plat-s3c/gpio.c b/arch/arm/plat-s3c/gpio.c
index d71dd6d..260fdc6 100644
--- a/arch/arm/plat-s3c/gpio.c
+++ b/arch/arm/plat-s3c/gpio.c
@@ -16,7 +16,7 @@
 #include <linux/io.h>
 #include <linux/gpio.h>
 
-#include <plat/gpio-core.h>
+#include <mach/gpio-core.h>
 
 #ifdef CONFIG_S3C_GPIO_TRACK
 struct s3c_gpio_chip *s3c_gpios[S3C_GPIO_END];
@@ -140,6 +140,15 @@ __init void s3c_gpiolib_add(struct s3c_gpio_chip *chip)
 	if (!gc->get)
 		gc->get = s3c_gpiolib_get;
 
+#ifdef CONFIG_PM
+	if (chip->pm != NULL) {
+		if (!chip->pm->save || !chip->pm->resume)
+			printk(KERN_ERR "gpio: %s has missing PM functions\n",
+			       gc->label);
+	} else
+		printk(KERN_ERR "gpio: %s has no PM function\n", gc->label);
+#endif
+
 	/* gpiochip_add() prints own failure message on error. */
 	ret = gpiochip_add(gc);
 	if (ret >= 0)
diff --git a/arch/arm/plat-s3c/include/plat/gpio-core.h b/arch/arm/plat-s3c/include/plat/gpio-core.h
index 2fc60a5..32af612 100644
--- a/arch/arm/plat-s3c/include/plat/gpio-core.h
+++ b/arch/arm/plat-s3c/include/plat/gpio-core.h
@@ -20,6 +20,18 @@
  * specific code.
 */
 
+struct s3c_gpio_chip;
+
+/**
+ * struct s3c_gpio_pm - power management (suspend/resume) information
+ * @save: Routine to save the state of the GPIO block
+ * @resume: Routine to resume the GPIO block.
+ */
+struct s3c_gpio_pm {
+	void (*save)(struct s3c_gpio_chip *chip);
+	void (*resume)(struct s3c_gpio_chip *chip);
+};
+
 struct s3c_gpio_cfg;
 
 /**
@@ -27,6 +39,7 @@ struct s3c_gpio_cfg;
  * @chip: The chip structure to be exported via gpiolib.
  * @base: The base pointer to the gpio configuration registers.
  * @config: special function and pull-resistor control information.
+ * @pm_save: Save information for suspend/resume support.
  *
  * This wrapper provides the necessary information for the Samsung
  * specific gpios being registered with gpiolib.
@@ -34,7 +47,11 @@ struct s3c_gpio_cfg;
 struct s3c_gpio_chip {
 	struct gpio_chip	chip;
 	struct s3c_gpio_cfg	*config;
+	struct s3c_gpio_pm	*pm;
 	void __iomem		*base;
+#ifdef CONFIG_PM
+	u32			pm_save[4];
+#endif
 };
 
 static inline struct s3c_gpio_chip *to_s3c_gpio(struct gpio_chip *gpc)
@@ -75,3 +92,16 @@ static inline struct s3c_gpio_chip *s3c_gpiolib_getchip(unsigned int chip)
 
 static inline void s3c_gpiolib_track(struct s3c_gpio_chip *chip) { }
 #endif
+
+#ifdef CONFIG_PM
+extern struct s3c_gpio_pm s3c_gpio_pm_1bit;
+extern struct s3c_gpio_pm s3c_gpio_pm_2bit;
+extern struct s3c_gpio_pm s3c_gpio_pm_4bit;
+#define __gpio_pm(x) x
+#else
+#define s3c_gpio_pm_1bit NULL
+#define s3c_gpio_pm_2bit NULL
+#define s3c_gpio_pm_4bit NULL
+#define __gpio_pm(x) NULL
+
+#endif /* CONFIG_PM */
diff --git a/arch/arm/plat-s3c/pm-gpio.c b/arch/arm/plat-s3c/pm-gpio.c
new file mode 100644
index 0000000..cfd326a
--- /dev/null
+++ b/arch/arm/plat-s3c/pm-gpio.c
@@ -0,0 +1,380 @@
+
+/* linux/arch/arm/plat-s3c/pm-gpio.c
+ *
+ * Copyright 2008 Openmoko, Inc.
+ * Copyright 2008 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *	http://armlinux.simtec.co.uk/
+ *
+ * S3C series GPIO PM code
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/kernel.h>
+#include <linux/sysdev.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+
+#include <mach/gpio-core.h>
+#include <plat/pm.h>
+
+/* PM GPIO helpers */
+
+#define OFFS_CON	(0x00)
+#define OFFS_DAT	(0x04)
+#define OFFS_UP		(0x08)
+
+static void s3c_gpio_pm_1bit_save(struct s3c_gpio_chip *chip)
+{
+	chip->pm_save[0] = __raw_readl(chip->base + OFFS_CON);
+	chip->pm_save[1] = __raw_readl(chip->base + OFFS_DAT);
+}
+
+static void s3c_gpio_pm_1bit_resume(struct s3c_gpio_chip *chip)
+{
+	void __iomem *base = chip->base;
+	u32 old_gpcon = __raw_readl(base + OFFS_CON);
+	u32 old_gpdat = __raw_readl(base + OFFS_DAT);
+	u32 gps_gpcon = chip->pm_save[0];
+	u32 gps_gpdat = chip->pm_save[1];
+	u32 gpcon;
+
+	/* GPACON only has one bit per control / data and no PULLUPs.
+	 * GPACON[x] = 0 => Output, 1 => SFN */
+
+	/* first set all SFN bits to SFN */
+
+	gpcon = old_gpcon | gps_gpcon;
+	__raw_writel(gpcon, base + OFFS_CON);
+
+	/* now set all the other bits */
+
+	__raw_writel(gps_gpdat, base + OFFS_DAT);
+	__raw_writel(gps_gpcon, base + OFFS_CON);
+
+	S3C_PMDBG("%s: CON %08x => %08x, DAT %08x => %08x\n",
+		  chip->chip.label, old_gpcon, gps_gpcon, old_gpdat, gps_gpdat);
+}
+
+struct s3c_gpio_pm s3c_gpio_pm_1bit = {
+	.save	= s3c_gpio_pm_1bit_save,
+	.resume = s3c_gpio_pm_1bit_resume,
+};
+
+static void s3c_gpio_pm_2bit_save(struct s3c_gpio_chip *chip)
+{
+	chip->pm_save[0] = __raw_readl(chip->base + OFFS_CON);
+	chip->pm_save[1] = __raw_readl(chip->base + OFFS_DAT);
+	chip->pm_save[2] = __raw_readl(chip->base + OFFS_UP);
+}
+
+/* Test whether the given masked+shifted bits of an GPIO configuration
+ * are one of the SFN (special function) modes. */
+
+static inline int is_sfn(unsigned long con)
+{
+	return con >= 2;
+}
+
+/* Test if the given masked+shifted GPIO configuration is an input */
+
+static inline int is_in(unsigned long con)
+{
+	return con == 0;
+}
+
+/* Test if the given masked+shifted GPIO configuration is an output */
+
+static inline int is_out(unsigned long con)
+{
+	return con == 1;
+}
+
+/**
+ * s3c_gpio_pm_2bit_resume() - restore the given GPIO bank
+ * @chip: The chip information to resume.
+ *
+ * Restore one of the GPIO banks that was saved during suspend. This is
+ * not as simple as once thought, due to the possibility of glitches
+ * from the order that the CON and DAT registers are set in.
+ *
+ * The three states the pin can be are {IN,OUT,SFN} which gives us 9
+ * combinations of changes to check. Three of these, if the pin stays
+ * in the same configuration can be discounted. This leaves us with
+ * the following:
+ *
+ * { IN => OUT }  Change DAT first
+ * { IN => SFN }  Change CON first
+ * { OUT => SFN } Change CON first, so new data will not glitch
+ * { OUT => IN }  Change CON first, so new data will not glitch
+ * { SFN => IN }  Change CON first
+ * { SFN => OUT } Change DAT first, so new data will not glitch [1]
+ *
+ * We do not currently deal with the UP registers as these control
+ * weak resistors, so a small delay in change should not need to bring
+ * these into the calculations.
+ *
+ * [1] this assumes that writing to a pin DAT whilst in SFN will set the
+ *     state for when it is next output.
+ */
+static void s3c_gpio_pm_2bit_resume(struct s3c_gpio_chip *chip)
+{
+	void __iomem *base = chip->base;
+	u32 old_gpcon = __raw_readl(base + OFFS_CON);
+	u32 old_gpdat = __raw_readl(base + OFFS_DAT);
+	u32 gps_gpcon = chip->pm_save[0];
+	u32 gps_gpdat = chip->pm_save[1];
+	u32 gpcon, old, new, mask;
+	u32 change_mask = 0x0;
+	int nr;
+
+	/* restore GPIO pull-up settings */
+	__raw_writel(chip->pm_save[2], base + OFFS_UP);
+
+	/* Create a change_mask of all the items that need to have
+	 * their CON value changed before their DAT value, so that
+	 * we minimise the work between the two settings.
+	 */
+
+	for (nr = 0, mask = 0x03; nr < 32; nr += 2, mask <<= 2) {
+		old = (old_gpcon & mask) >> nr;
+		new = (gps_gpcon & mask) >> nr;
+
+		/* If there is no change, then skip */
+
+		if (old == new)
+			continue;
+
+		/* If both are special function, then skip */
+
+		if (is_sfn(old) && is_sfn(new))
+			continue;
+
+		/* Change is IN => OUT, do not change now */
+
+		if (is_in(old) && is_out(new))
+			continue;
+
+		/* Change is SFN => OUT, do not change now */
+
+		if (is_sfn(old) && is_out(new))
+			continue;
+
+		/* We should now be at the case of IN=>SFN,
+		 * OUT=>SFN, OUT=>IN, SFN=>IN. */
+
+		change_mask |= mask;
+	}
+
+
+	/* Write the new CON settings */
+
+	gpcon = old_gpcon & ~change_mask;
+	gpcon |= gps_gpcon & change_mask;
+
+	__raw_writel(gpcon, base + OFFS_CON);
+
+	/* Now change any items that require DAT,CON */
+
+	__raw_writel(gps_gpdat, base + OFFS_DAT);
+	__raw_writel(gps_gpcon, base + OFFS_CON);
+
+	S3C_PMDBG("%s: CON %08x => %08x, DAT %08x => %08x\n",
+		  chip->chip.label, old_gpcon, gps_gpcon, old_gpdat, gps_gpdat);
+}
+
+struct s3c_gpio_pm s3c_gpio_pm_2bit = {
+	.save	= s3c_gpio_pm_2bit_save,
+	.resume = s3c_gpio_pm_2bit_resume,
+};
+
+#ifdef CONFIG_ARCH_S3C64XX
+static void s3c_gpio_pm_4bit_save(struct s3c_gpio_chip *chip)
+{
+	chip->pm_save[1] = __raw_readl(chip->base + OFFS_CON);
+	chip->pm_save[2] = __raw_readl(chip->base + OFFS_DAT);
+	chip->pm_save[3] = __raw_readl(chip->base + OFFS_UP);
+
+	if (chip->chip.ngpio > 8)
+		chip->pm_save[0] = __raw_readl(chip->base - 4);
+}
+
+static u32 s3c_gpio_pm_4bit_mask(u32 old_gpcon, u32 gps_gpcon)
+{
+	u32 old, new, mask;
+	u32 change_mask = 0x0;
+	int nr;
+
+	for (nr = 0, mask = 0x0f; nr < 16; nr += 4, mask <<= 4) {
+		old = (old_gpcon & mask) >> nr;
+		new = (gps_gpcon & mask) >> nr;
+
+		/* If there is no change, then skip */
+
+		if (old == new)
+			continue;
+
+		/* If both are special function, then skip */
+
+		if (is_sfn(old) && is_sfn(new))
+			continue;
+
+		/* Change is IN => OUT, do not change now */
+
+		if (is_in(old) && is_out(new))
+			continue;
+
+		/* Change is SFN => OUT, do not change now */
+
+		if (is_sfn(old) && is_out(new))
+			continue;
+
+		/* We should now be at the case of IN=>SFN,
+		 * OUT=>SFN, OUT=>IN, SFN=>IN. */
+
+		change_mask |= mask;
+	}
+
+	return change_mask;
+}
+
+static void s3c_gpio_pm_4bit_con(struct s3c_gpio_chip *chip, int index)
+{
+	void __iomem *con = chip->base + (index * 4);
+	u32 old_gpcon = __raw_readl(con);
+	u32 gps_gpcon = chip->pm_save[index + 1];
+	u32 gpcon, mask;
+
+	mask = s3c_gpio_pm_4bit_mask(old_gpcon, gps_gpcon);
+
+	gpcon = old_gpcon & ~mask;
+	gpcon |= gps_gpcon & mask;
+
+	__raw_writel(gpcon, con);
+}
+
+static void s3c_gpio_pm_4bit_resume(struct s3c_gpio_chip *chip)
+{
+	void __iomem *base = chip->base;
+	u32 old_gpcon[2];
+	u32 old_gpdat = __raw_readl(base + OFFS_DAT);
+	u32 gps_gpdat = chip->pm_save[2];
+
+	/* First, modify the CON settings */
+
+	old_gpcon[0] = 0;
+	old_gpcon[1] = __raw_readl(base + OFFS_CON);
+
+	s3c_gpio_pm_4bit_con(chip, 0);
+	if (chip->chip.ngpio > 8) {
+		old_gpcon[0] = __raw_readl(base - 4);
+		s3c_gpio_pm_4bit_con(chip, -1);
+	}
+
+	/* Now change the configurations that require DAT,CON */
+
+	__raw_writel(chip->pm_save[2], base + OFFS_DAT);
+	__raw_writel(chip->pm_save[1], base + OFFS_CON);
+	if (chip->chip.ngpio > 8)
+		__raw_writel(chip->pm_save[0], base - 4);
+
+	__raw_writel(chip->pm_save[2], base + OFFS_DAT);
+	__raw_writel(chip->pm_save[3], base + OFFS_UP);
+
+	if (chip->chip.ngpio > 8) {
+		S3C_PMDBG("%s: CON4 %08x,%08x => %08x,%08x, DAT %08x => %08x\n",
+			  chip->chip.label, old_gpcon[0], old_gpcon[1],
+			  __raw_readl(base - 4),
+			  __raw_readl(base + OFFS_CON),
+			  old_gpdat, gps_gpdat);
+	} else
+		S3C_PMDBG("%s: CON4 %08x => %08x, DAT %08x => %08x\n",
+			  chip->chip.label, old_gpcon[1],
+			  __raw_readl(base + OFFS_CON),
+			  old_gpdat, gps_gpdat);
+}
+
+struct s3c_gpio_pm s3c_gpio_pm_4bit = {
+	.save	= s3c_gpio_pm_4bit_save,
+	.resume = s3c_gpio_pm_4bit_resume,
+};
+#endif /* CONFIG_ARCH_S3C64XX */
+
+/**
+ * s3c_pm_save_gpio() - save gpio chip data for suspend
+ * @ourchip: The chip for suspend.
+ */
+static void s3c_pm_save_gpio(struct s3c_gpio_chip *ourchip)
+{
+	struct s3c_gpio_pm *pm = ourchip->pm;
+
+	if (pm == NULL || pm->save == NULL)
+		S3C_PMDBG("%s: no pm for %s\n", __func__, ourchip->chip.label);
+	else
+		pm->save(ourchip);
+}
+
+/**
+ * s3c_pm_save_gpios() - Save the state of the GPIO banks.
+ *
+ * For all the GPIO banks, save the state of each one ready for going
+ * into a suspend mode.
+ */
+void s3c_pm_save_gpios(void)
+{
+	struct s3c_gpio_chip *ourchip;
+	unsigned int gpio_nr;
+
+	for (gpio_nr = 0; gpio_nr < S3C_GPIO_END; gpio_nr++) {
+		ourchip = s3c_gpiolib_getchip(gpio_nr);
+		if (!ourchip)
+			continue;
+
+		s3c_pm_save_gpio(ourchip);
+
+		S3C_PMDBG("%s: save %08x,%08x,%08x,%08x\n",
+			  ourchip->chip.label,
+			  ourchip->pm_save[0],
+			  ourchip->pm_save[1],
+			  ourchip->pm_save[2],
+			  ourchip->pm_save[3]);
+
+		gpio_nr += ourchip->chip.ngpio;
+		gpio_nr += CONFIG_S3C_GPIO_SPACE;
+	}
+}
+
+/**
+ * s3c_pm_resume_gpio() - restore gpio chip data after suspend
+ * @ourchip: The suspended chip.
+ */
+static void s3c_pm_resume_gpio(struct s3c_gpio_chip *ourchip)
+{
+	struct s3c_gpio_pm *pm = ourchip->pm;
+
+	if (pm == NULL || pm->resume == NULL)
+		S3C_PMDBG("%s: no pm for %s\n", __func__, ourchip->chip.label);
+	else
+		pm->resume(ourchip);
+}
+
+void s3c_pm_restore_gpios(void)
+{
+	struct s3c_gpio_chip *ourchip;
+	unsigned int gpio_nr;
+
+	for (gpio_nr = 0; gpio_nr < S3C_GPIO_END; gpio_nr++) {
+		ourchip = s3c_gpiolib_getchip(gpio_nr);
+		if (!ourchip)
+			continue;
+
+		s3c_pm_resume_gpio(ourchip);
+
+		gpio_nr += ourchip->chip.ngpio;
+		gpio_nr += CONFIG_S3C_GPIO_SPACE;
+	}
+}