pinctrl: mcp23s08: switch to regmap caching

Instead of using custom caching, this switches to regmap based
caching. Before the conversion the debugfs file used uncached
values, so that it was easily possible to see power-loss related
problems. The new code will check and recover at this place.

The patch will also ensure, that irqs are not cleared by checking
register status in debugfs.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-mcp23s08.c

@@ -67,14 +67,13 @@ struct mcp23s08 {
 	bool			irq_active_high;
 	bool			reg_shift;
 
-	u16			cache[11];
 	u16			irq_rise;
 	u16			irq_fall;
 	int			irq;
 	bool			irq_controller;
-	/* lock protects the cached values */
+	int			cached_gpio;
+	/* lock protects regmap access with bypass/cache flags */
 	struct mutex		lock;
-	struct mutex		irq_lock;
 
 	struct gpio_chip	chip;
 
@@ -85,20 +84,92 @@ struct mcp23s08 {
 	struct pinctrl_desc	pinctrl_desc;
 };
 
+static const struct reg_default mcp23x08_defaults[] = {
+	{.reg = MCP_IODIR,		.def = 0xff},
+	{.reg = MCP_IPOL,		.def = 0x00},
+	{.reg = MCP_GPINTEN,		.def = 0x00},
+	{.reg = MCP_DEFVAL,		.def = 0x00},
+	{.reg = MCP_INTCON,		.def = 0x00},
+	{.reg = MCP_IOCON,		.def = 0x00},
+	{.reg = MCP_GPPU,		.def = 0x00},
+	{.reg = MCP_OLAT,		.def = 0x00},
+};
+
+static const struct regmap_range mcp23x08_volatile_range = {
+	.range_min = MCP_INTF,
+	.range_max = MCP_GPIO,
+};
+
+static const struct regmap_access_table mcp23x08_volatile_table = {
+	.yes_ranges = &mcp23x08_volatile_range,
+	.n_yes_ranges = 1,
+};
+
+static const struct regmap_range mcp23x08_precious_range = {
+	.range_min = MCP_GPIO,
+	.range_max = MCP_GPIO,
+};
+
+static const struct regmap_access_table mcp23x08_precious_table = {
+	.yes_ranges = &mcp23x08_precious_range,
+	.n_yes_ranges = 1,
+};
+
 static const struct regmap_config mcp23x08_regmap = {
 	.reg_bits = 8,
 	.val_bits = 8,
 
 	.reg_stride = 1,
+	.volatile_table = &mcp23x08_volatile_table,
+	.precious_table = &mcp23x08_precious_table,
+	.reg_defaults = mcp23x08_defaults,
+	.num_reg_defaults = ARRAY_SIZE(mcp23x08_defaults),
+	.cache_type = REGCACHE_FLAT,
 	.max_register = MCP_OLAT,
 };
 
+static const struct reg_default mcp23x16_defaults[] = {
+	{.reg = MCP_IODIR << 1,		.def = 0xffff},
+	{.reg = MCP_IPOL << 1,		.def = 0x0000},
+	{.reg = MCP_GPINTEN << 1,	.def = 0x0000},
+	{.reg = MCP_DEFVAL << 1,	.def = 0x0000},
+	{.reg = MCP_INTCON << 1,	.def = 0x0000},
+	{.reg = MCP_IOCON << 1,		.def = 0x0000},
+	{.reg = MCP_GPPU << 1,		.def = 0x0000},
+	{.reg = MCP_OLAT << 1,		.def = 0x0000},
+};
+
+static const struct regmap_range mcp23x16_volatile_range = {
+	.range_min = MCP_INTF << 1,
+	.range_max = MCP_GPIO << 1,
+};
+
+static const struct regmap_access_table mcp23x16_volatile_table = {
+	.yes_ranges = &mcp23x16_volatile_range,
+	.n_yes_ranges = 1,
+};
+
+static const struct regmap_range mcp23x16_precious_range = {
+	.range_min = MCP_GPIO << 1,
+	.range_max = MCP_GPIO << 1,
+};
+
+static const struct regmap_access_table mcp23x16_precious_table = {
+	.yes_ranges = &mcp23x16_precious_range,
+	.n_yes_ranges = 1,
+};
+
 static const struct regmap_config mcp23x17_regmap = {
 	.reg_bits = 8,
 	.val_bits = 16,
 
 	.reg_stride = 2,
 	.max_register = MCP_OLAT << 1,
+	.volatile_table = &mcp23x16_volatile_table,
+	.precious_table = &mcp23x16_precious_table,
+	.reg_defaults = mcp23x16_defaults,
+	.num_reg_defaults = ARRAY_SIZE(mcp23x16_defaults),
+	.cache_type = REGCACHE_FLAT,
 	.val_format_endian = REGMAP_ENDIAN_LITTLE,
 };
 
@@ -112,27 +183,19 @@ static int mcp_write(struct mcp23s08 *mcp, unsigned int reg, unsigned int val)
 	return regmap_write(mcp->regmap, reg << mcp->reg_shift, val);
 }
 
-static int mcp_set_bit(struct mcp23s08 *mcp, unsigned int reg,
-		       unsigned int pin, bool enabled)
+static int mcp_set_mask(struct mcp23s08 *mcp, unsigned int reg,
+		       unsigned int mask, bool enabled)
 {
 	u16 val  = enabled ? 0xffff : 0x0000;
-	u16 mask = BIT(pin);
 	return regmap_update_bits(mcp->regmap, reg << mcp->reg_shift,
 				  mask, val);
 }
 
-static int mcp_update_cache(struct mcp23s08 *mcp)
+static int mcp_set_bit(struct mcp23s08 *mcp, unsigned int reg,
+		       unsigned int pin, bool enabled)
 {
-	int ret, reg, i;
-
-	for (i = 0; i < ARRAY_SIZE(mcp->cache); i++) {
-		ret = mcp_read(mcp, i, &reg);
-		if (ret < 0)
-			return ret;
-		mcp->cache[i] = reg;
-	}
-
-	return 0;
+	u16 mask = BIT(pin);
+	return mcp_set_mask(mcp, reg, mask, enabled);
 }
 
 static const struct pinctrl_pin_desc mcp23x08_pins[] = {
@@ -336,9 +399,9 @@ static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
 	int status;
 
 	mutex_lock(&mcp->lock);
-	mcp->cache[MCP_IODIR] |= (1 << offset);
-	status = mcp_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
+	status = mcp_set_bit(mcp, MCP_IODIR, offset, true);
 	mutex_unlock(&mcp->lock);
+
 	return status;
 }
 
@@ -353,33 +416,27 @@ static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
 	ret = mcp_read(mcp, MCP_GPIO, &status);
 	if (ret < 0)
 		status = 0;
-	else {
-		mcp->cache[MCP_GPIO] = status;
+	else
 		status = !!(status & (1 << offset));
-	}
+
+	mcp->cached_gpio = status;
+
 	mutex_unlock(&mcp->lock);
 	return status;
 }
 
-static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
+static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, bool value)
 {
-	unsigned olat = mcp->cache[MCP_OLAT];
-
-	if (value)
-		olat |= mask;
-	else
-		olat &= ~mask;
-	mcp->cache[MCP_OLAT] = olat;
-	return mcp_write(mcp, MCP_OLAT, olat);
+	return mcp_set_mask(mcp, MCP_OLAT, mask, value);
 }
 
 static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct mcp23s08	*mcp = gpiochip_get_data(chip);
-	unsigned mask = 1 << offset;
+	unsigned mask = BIT(offset);
 
 	mutex_lock(&mcp->lock);
-	__mcp23s08_set(mcp, mask, value);
+	__mcp23s08_set(mcp, mask, !!value);
 	mutex_unlock(&mcp->lock);
 }
 
@@ -387,14 +444,13 @@ static int
 mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct mcp23s08	*mcp = gpiochip_get_data(chip);
-	unsigned mask = 1 << offset;
+	unsigned mask = BIT(offset);
 	int status;
 
 	mutex_lock(&mcp->lock);
 	status = __mcp23s08_set(mcp, mask, value);
 	if (status == 0) {
-		mcp->cache[MCP_IODIR] &= ~mask;
-		status = mcp_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
+		status = mcp_set_mask(mcp, MCP_IODIR, mask, false);
 	}
 	mutex_unlock(&mcp->lock);
 	return status;
@@ -404,7 +460,7 @@ mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
 static irqreturn_t mcp23s08_irq(int irq, void *data)
 {
 	struct mcp23s08 *mcp = data;
-	int intcap, intf, i, gpio, gpio_orig, intcap_mask;
+	int intcap, intcon, intf, i, gpio, gpio_orig, intcap_mask, defval;
 	unsigned int child_irq;
 	bool intf_set, intcap_changed, gpio_bit_changed,
 		defval_changed, gpio_set;
@@ -415,25 +471,31 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 		return IRQ_HANDLED;
 	}
 
-	mcp->cache[MCP_INTF] = intf;
-
 	if (mcp_read(mcp, MCP_INTCAP, &intcap) < 0) {
 		mutex_unlock(&mcp->lock);
 		return IRQ_HANDLED;
 	}
 
-	mcp->cache[MCP_INTCAP] = intcap;
+	if (mcp_read(mcp, MCP_INTCON, &intcon) < 0) {
+		mutex_unlock(&mcp->lock);
+		return IRQ_HANDLED;
+	}
+
+	if (mcp_read(mcp, MCP_DEFVAL, &defval) < 0) {
+		mutex_unlock(&mcp->lock);
+		return IRQ_HANDLED;
+	}
 
 	/* This clears the interrupt(configurable on S18) */
 	if (mcp_read(mcp, MCP_GPIO, &gpio) < 0) {
 		mutex_unlock(&mcp->lock);
 		return IRQ_HANDLED;
 	}
-	gpio_orig = mcp->cache[MCP_GPIO];
-	mcp->cache[MCP_GPIO] = gpio;
+	gpio_orig = mcp->cached_gpio;
+	mcp->cached_gpio = gpio;
 	mutex_unlock(&mcp->lock);
 
-	if (mcp->cache[MCP_INTF] == 0) {
+	if (intf == 0) {
 		/* There is no interrupt pending */
 		return IRQ_HANDLED;
 	}
@@ -461,7 +523,7 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 		 * to see if the input has changed.
 		 */
 
-		intf_set = BIT(i) & mcp->cache[MCP_INTF];
+		intf_set = intf & BIT(i);
 		if (i < 8 && intf_set)
 			intcap_mask = 0x00FF;
 		else if (i >= 8 && intf_set)
@@ -470,14 +532,14 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 			intcap_mask = 0x00;
 
 		intcap_changed = (intcap_mask &
-			(BIT(i) & mcp->cache[MCP_INTCAP])) !=
+			(intcap & BIT(i))) !=
 			(intcap_mask & (BIT(i) & gpio_orig));
-		gpio_set = BIT(i) & mcp->cache[MCP_GPIO];
+		gpio_set = BIT(i) & gpio;
 		gpio_bit_changed = (BIT(i) & gpio_orig) !=
-			(BIT(i) & mcp->cache[MCP_GPIO]);
-		defval_changed = (BIT(i) & mcp->cache[MCP_INTCON]) &&
-			((BIT(i) & mcp->cache[MCP_GPIO]) !=
-			(BIT(i) & mcp->cache[MCP_DEFVAL]));
+			(BIT(i) & gpio);
+		defval_changed = (BIT(i) & intcon) &&
+			((BIT(i) & gpio) !=
+			(BIT(i) & defval));
 
 		if (((gpio_bit_changed || intcap_changed) &&
 			(BIT(i) & mcp->irq_rise) && gpio_set) ||
@@ -498,7 +560,7 @@ static void mcp23s08_irq_mask(struct irq_data *data)
 	struct mcp23s08 *mcp = gpiochip_get_data(gc);
 	unsigned int pos = data->hwirq;
 
-	mcp->cache[MCP_GPINTEN] &= ~BIT(pos);
+	mcp_set_bit(mcp, MCP_GPINTEN, pos, false);
 }
 
 static void mcp23s08_irq_unmask(struct irq_data *data)
@@ -507,7 +569,7 @@ static void mcp23s08_irq_unmask(struct irq_data *data)
 	struct mcp23s08 *mcp = gpiochip_get_data(gc);
 	unsigned int pos = data->hwirq;
 
-	mcp->cache[MCP_GPINTEN] |= BIT(pos);
+	mcp_set_bit(mcp, MCP_GPINTEN, pos, true);
 }
 
 static int mcp23s08_irq_set_type(struct irq_data *data, unsigned int type)
@@ -518,23 +580,23 @@ static int mcp23s08_irq_set_type(struct irq_data *data, unsigned int type)
 	int status = 0;
 
 	if ((type & IRQ_TYPE_EDGE_BOTH) == IRQ_TYPE_EDGE_BOTH) {
-		mcp->cache[MCP_INTCON] &= ~BIT(pos);
+		mcp_set_bit(mcp, MCP_INTCON, pos, false);
 		mcp->irq_rise |= BIT(pos);
 		mcp->irq_fall |= BIT(pos);
 	} else if (type & IRQ_TYPE_EDGE_RISING) {
-		mcp->cache[MCP_INTCON] &= ~BIT(pos);
+		mcp_set_bit(mcp, MCP_INTCON, pos, false);
 		mcp->irq_rise |= BIT(pos);
 		mcp->irq_fall &= ~BIT(pos);
 	} else if (type & IRQ_TYPE_EDGE_FALLING) {
-		mcp->cache[MCP_INTCON] &= ~BIT(pos);
+		mcp_set_bit(mcp, MCP_INTCON, pos, false);
 		mcp->irq_rise &= ~BIT(pos);
 		mcp->irq_fall |= BIT(pos);
 	} else if (type & IRQ_TYPE_LEVEL_HIGH) {
-		mcp->cache[MCP_INTCON] |= BIT(pos);
-		mcp->cache[MCP_DEFVAL] &= ~BIT(pos);
+		mcp_set_bit(mcp, MCP_INTCON, pos, true);
+		mcp_set_bit(mcp, MCP_DEFVAL, pos, false);
 	} else if (type & IRQ_TYPE_LEVEL_LOW) {
-		mcp->cache[MCP_INTCON] |= BIT(pos);
-		mcp->cache[MCP_DEFVAL] |= BIT(pos);
+		mcp_set_bit(mcp, MCP_INTCON, pos, true);
+		mcp_set_bit(mcp, MCP_DEFVAL, pos, true);
 	} else
 		return -EINVAL;
 
@@ -546,7 +608,8 @@ static void mcp23s08_irq_bus_lock(struct irq_data *data)
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
 	struct mcp23s08 *mcp = gpiochip_get_data(gc);
 
-	mutex_lock(&mcp->irq_lock);
+	mutex_lock(&mcp->lock);
+	regcache_cache_only(mcp->regmap, true);
 }
 
 static void mcp23s08_irq_bus_unlock(struct irq_data *data)
@@ -554,12 +617,10 @@ static void mcp23s08_irq_bus_unlock(struct irq_data *data)
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
 	struct mcp23s08 *mcp = gpiochip_get_data(gc);
 
-	mutex_lock(&mcp->lock);
-	mcp_write(mcp, MCP_GPINTEN, mcp->cache[MCP_GPINTEN]);
-	mcp_write(mcp, MCP_DEFVAL, mcp->cache[MCP_DEFVAL]);
-	mcp_write(mcp, MCP_INTCON, mcp->cache[MCP_INTCON]);
+	regcache_cache_only(mcp->regmap, false);
+	regcache_sync(mcp->regmap);
+
 	mutex_unlock(&mcp->lock);
-	mutex_unlock(&mcp->irq_lock);
 }
 
 static struct irq_chip mcp23s08_irq_chip = {
@@ -577,8 +638,6 @@ static int mcp23s08_irq_setup(struct mcp23s08 *mcp)
 	int err;
 	unsigned long irqflags = IRQF_ONESHOT | IRQF_SHARED;
 
-	mutex_init(&mcp->irq_lock);
-
 	if (mcp->irq_active_high)
 		irqflags |= IRQF_TRIGGER_HIGH;
 	else
@@ -617,6 +676,47 @@ static int mcp23s08_irq_setup(struct mcp23s08 *mcp)
 
 #include <linux/seq_file.h>
 
+/*
+ * This compares the chip's registers with the register
+ * cache and corrects any incorrectly set register. This
+ * can be used to fix state for MCP23xxx, that temporary
+ * lost its power supply.
+ */
+#define MCP23S08_CONFIG_REGS 8
+static int __check_mcp23s08_reg_cache(struct mcp23s08 *mcp)
+{
+	int cached[MCP23S08_CONFIG_REGS];
+	int err = 0, i;
+
+	/* read cached config registers */
+	for (i = 0; i < MCP23S08_CONFIG_REGS; i++) {
+		err = mcp_read(mcp, i, &cached[i]);
+		if (err)
+			goto out;
+	}
+
+	regcache_cache_bypass(mcp->regmap, true);
+
+	for (i = 0; i < MCP23S08_CONFIG_REGS; i++) {
+		int uncached;
+		err = mcp_read(mcp, i, &uncached);
+		if (err)
+			goto out;
+
+		if (uncached != cached[i]) {
+			dev_err(mcp->dev, "restoring reg 0x%02x from 0x%04x to 0x%04x (power-loss?)\n",
+				i, uncached, cached[i]);
+			mcp_write(mcp, i, cached[i]);
+		}
+	}
+
+out:
+	if (err)
+		dev_err(mcp->dev, "read error: reg=%02x, err=%d", i, err);
+	regcache_cache_bypass(mcp->regmap, false);
+	return err;
+}
+
 /*
  * This shows more info than the generic gpio dump code:
  * pullups, deglitching, open drain drive.
@@ -627,6 +727,7 @@ static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 	char		bank;
 	int		t;
 	unsigned	mask;
+	int iodir, gpio, gppu;
 
 	mcp = gpiochip_get_data(chip);
 
@@ -634,14 +735,30 @@ static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 	bank = '0' + ((mcp->addr >> 1) & 0x7);
 
 	mutex_lock(&mcp->lock);
-	t = mcp_update_cache(mcp);
-	if (t < 0) {
-		seq_printf(s, " I/O ERROR %d\n", t);
+
+	t = __check_mcp23s08_reg_cache(mcp);
+	if (t) {
+		seq_printf(s, " I/O Error\n");
+		goto done;
+	}
+	t = mcp_read(mcp, MCP_IODIR, &iodir);
+	if (t) {
+		seq_printf(s, " I/O Error\n");
+		goto done;
+	}
+	t = mcp_read(mcp, MCP_GPIO, &gpio);
+	if (t) {
+		seq_printf(s, " I/O Error\n");
+		goto done;
+	}
+	t = mcp_read(mcp, MCP_GPPU, &gppu);
+	if (t) {
+		seq_printf(s, " I/O Error\n");
 		goto done;
 	}
 
-	for (t = 0, mask = 1; t < chip->ngpio; t++, mask <<= 1) {
-		const char	*label;
+	for (t = 0, mask = BIT(0); t < chip->ngpio; t++, mask <<= 1) {
+		const char *label;
 
 		label = gpiochip_is_requested(chip, t);
 		if (!label)
@@ -649,9 +766,9 @@ static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 
 		seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
 			chip->base + t, bank, t, label,
-			(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
-			(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
-			(mcp->cache[MCP_GPPU] & mask) ? "up" : "  ");
+			(iodir & mask) ? "in " : "out",
+			(gpio & mask) ? "hi" : "lo",
+			(gppu & mask) ? "up" : "  ");
 		/* NOTE:  ignoring the irq-related registers */
 		seq_puts(s, "\n");
 	}
@@ -782,26 +899,6 @@ static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
 			goto fail;
 	}
 
-	ret = mcp_update_cache(mcp);
-	if (ret < 0)
-		goto fail;
-
-	/* disable inverter on input */
-	if (mcp->cache[MCP_IPOL] != 0) {
-		mcp->cache[MCP_IPOL] = 0;
-		ret = mcp_write(mcp, MCP_IPOL, 0);
-		if (ret < 0)
-			goto fail;
-	}
-
-	/* disable irqs */
-	if (mcp->cache[MCP_GPINTEN] != 0) {
-		mcp->cache[MCP_GPINTEN] = 0;
-		ret = mcp_write(mcp, MCP_GPINTEN, 0);
-		if (ret < 0)
-			goto fail;
-	}
-
 	ret = gpiochip_add_data(&mcp->chip, mcp);
 	if (ret < 0)
 		goto fail;