GPIO: CREG: improve flexibility of hsdk-creg-gpio driver

CREG GPIO is a driver for weird soc-specific output ports, which are
controlled by some fields in memory mapped register.

Example:

31                 9        7        5           0   < bit number
|                  |        |        |           |
[     not used     | gpio-1 | gpio-0 | <-shift-> ]   < 32 bit register
                       ^        ^
                       |        |
                write 0x2 == set output to "1" (activate)
                write 0x3 == set output to "0" (deactivate)

As of tooday we only support fixed (hardcoded) bit per gpio line,
activate / deactivatei and shift values. Fix that by read them from
device tree to be able to use this driver for other boards.

Remove "hsdk" prefix from compatible string as this driver can be
used with different boards like HSDK, AXS101, AXS103, etc.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

arch/arc/dts/hsdk.dts

@@ -101,11 +101,16 @@
 	};
 
 	cs_gpio: gpio@f00014b0 {
-		compatible = "snps,hsdk-creg-gpio";
+		compatible = "snps,creg-gpio";
 		reg = <0xf00014b0 0x4>;
 		gpio-controller;
 		#gpio-cells = <1>;
 		gpio-bank-name = "hsdk-spi-cs";
 		gpio-count = <1>;
+		gpio-first-shift = <0>;
+		gpio-bit-per-line = <2>;
+		gpio-activate-val = <2>;
+		gpio-deactivate-val = <3>;
+		gpio-default-val = <1>;
 	};
 };

drivers/gpio/hsdk-creg-gpio.c

@@ -16,25 +16,24 @@
 #include <errno.h>
 #include <linux/printk.h>
 
-#define HSDK_CREG_MAX_GPIO	8
-
-#define GPIO_ACTIVATE		0x2
-#define GPIO_DEACTIVATE		0x3
-#define GPIO_PIN_MASK		0x3
-#define BIT_PER_GPIO		2
+#define DRV_NAME	"gpio_creg"
 
 struct hsdk_creg_gpio {
-	uint32_t *regs;
+	u32	*regs;
+	u8	shift;
+	u8	activate;
+	u8	deactivate;
+	u8	bit_per_gpio;
 };
 
 static int hsdk_creg_gpio_set_value(struct udevice *dev, unsigned oft, int val)
 {
 	struct hsdk_creg_gpio *hcg = dev_get_priv(dev);
-	uint32_t reg = readl(hcg->regs);
-	uint32_t cmd = val ? GPIO_DEACTIVATE : GPIO_ACTIVATE;
+	u8 reg_shift = oft * hcg->bit_per_gpio + hcg->shift;
+	u32 reg = readl(hcg->regs);
 
-	reg &= ~(GPIO_PIN_MASK << (oft * BIT_PER_GPIO));
-	reg |=  (cmd << (oft * BIT_PER_GPIO));
+	reg &= ~(GENMASK(hcg->bit_per_gpio - 1, 0) << reg_shift);
+	reg |=  ((val ? hcg->deactivate : hcg->activate) << reg_shift);
 
 	writel(reg, hcg->regs);
 
@@ -51,7 +50,9 @@ static int hsdk_creg_gpio_direction_output(struct udevice *dev, unsigned oft,
 
 static int hsdk_creg_gpio_direction_input(struct udevice *dev, unsigned oft)
 {
-	pr_err("hsdk-creg-gpio can't be used as input!\n");
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	pr_err("%s can't be used as input!\n", uc_priv->bank_name);
 
 	return -ENOTSUPP;
 }
@@ -59,10 +60,11 @@ static int hsdk_creg_gpio_direction_input(struct udevice *dev, unsigned oft)
 static int hsdk_creg_gpio_get_value(struct udevice *dev, unsigned int oft)
 {
 	struct hsdk_creg_gpio *hcg = dev_get_priv(dev);
-	uint32_t val = readl(hcg->regs);
+	u32 val = readl(hcg->regs);
 
-	val = (val >> (oft * BIT_PER_GPIO)) & GPIO_PIN_MASK;
-	return (val == GPIO_DEACTIVATE) ? 1 : 0;
+	val >>= oft * hcg->bit_per_gpio + hcg->shift;
+	val &= GENMASK(hcg->bit_per_gpio - 1, 0);
+	return (val == hcg->deactivate) ? 1 : 0;
 }
 
 static const struct dm_gpio_ops hsdk_creg_gpio_ops = {
@@ -76,17 +78,74 @@ static int hsdk_creg_gpio_probe(struct udevice *dev)
 {
 	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
 	struct hsdk_creg_gpio *hcg = dev_get_priv(dev);
+	u32 shift, bit_per_gpio, activate, deactivate, gpio_count;
+	const u8 *defaults;
 
-	hcg->regs = (uint32_t *)devfdt_get_addr_ptr(dev);
-
-	uc_priv->gpio_count = dev_read_u32_default(dev, "gpio-count", 1);
-	if (uc_priv->gpio_count > HSDK_CREG_MAX_GPIO)
-		uc_priv->gpio_count = HSDK_CREG_MAX_GPIO;
+	hcg->regs = (u32 *)devfdt_get_addr_ptr(dev);
+	gpio_count = dev_read_u32_default(dev, "gpio-count", 1);
+	shift = dev_read_u32_default(dev, "gpio-first-shift", 0);
+	bit_per_gpio = dev_read_u32_default(dev, "gpio-bit-per-line", 1);
+	activate = dev_read_u32_default(dev, "gpio-activate-val", 1);
+	deactivate = dev_read_u32_default(dev, "gpio-deactivate-val", 0);
+	defaults = dev_read_u8_array_ptr(dev, "gpio-default-val", gpio_count);
 
 	uc_priv->bank_name = dev_read_string(dev, "gpio-bank-name");
 	if (!uc_priv->bank_name)
 		uc_priv->bank_name = dev_read_name(dev);
 
+	if (!bit_per_gpio) {
+		pr_err("%s: 'gpio-bit-per-line' can't be 0\n",
+		       uc_priv->bank_name);
+
+		return -EINVAL;
+	}
+
+	if (!gpio_count) {
+		pr_err("%s: 'gpio-count' can't be 0\n",
+		       uc_priv->bank_name);
+
+		return -EINVAL;
+	}
+
+	if ((gpio_count * bit_per_gpio + shift) > 32) {
+		pr_err("%s: u32 io register overflow: try to use %u bits\n",
+		       uc_priv->bank_name, gpio_count * bit_per_gpio + shift);
+
+		return -EINVAL;
+	}
+
+	if (GENMASK(31, bit_per_gpio) & activate) {
+		pr_err("%s: 'gpio-activate-val' can't be more than %lu\n",
+		       uc_priv->bank_name, GENMASK(bit_per_gpio - 1, 0));
+
+		return -EINVAL;
+	}
+
+	if (GENMASK(31, bit_per_gpio) & deactivate) {
+		pr_err("%s: 'gpio-deactivate-val' can't be more than %lu\n",
+		       uc_priv->bank_name, GENMASK(bit_per_gpio - 1, 0));
+
+		return -EINVAL;
+	}
+
+	if (activate == deactivate) {
+		pr_err("%s: 'gpio-deactivate-val' and 'gpio-activate-val' can't be equal\n",
+		       uc_priv->bank_name);
+
+		return -EINVAL;
+	}
+
+	hcg->shift = (u8)shift;
+	hcg->bit_per_gpio = (u8)bit_per_gpio;
+	hcg->activate = (u8)activate;
+	hcg->deactivate = (u8)deactivate;
+	uc_priv->gpio_count = gpio_count;
+
+	/* Setup default GPIO value if we have "gpio-default-val" array */
+	if (defaults)
+		for (u8 i = 0; i < gpio_count; i++)
+			hsdk_creg_gpio_set_value(dev, i, defaults[i]);
+
 	pr_debug("%s GPIO [0x%p] controller with %d gpios probed\n",
 		 uc_priv->bank_name, hcg->regs, uc_priv->gpio_count);
 
@@ -94,12 +153,12 @@ static int hsdk_creg_gpio_probe(struct udevice *dev)
 }
 
 static const struct udevice_id hsdk_creg_gpio_ids[] = {
-	{ .compatible = "snps,hsdk-creg-gpio" },
+	{ .compatible = "snps,creg-gpio" },
 	{ }
 };
 
 U_BOOT_DRIVER(gpio_hsdk_creg) = {
-	.name	= "gpio_hsdk_creg",
+	.name	= DRV_NAME,
 	.id	= UCLASS_GPIO,
 	.ops	= &hsdk_creg_gpio_ops,
 	.probe	= hsdk_creg_gpio_probe,