realtek: always require SMI bus ID for RTL8231

The SMI bus ID for RTL8231 currently defaults to 0, and can be
overridden from the devicetree. However, there is no value check on the
DT-provided value, aside from masking which would only cause value
wrap-around.

Change the driver to always require the "indirect-access-bus-id"
property, as there is no real reason to use 0 as default, and perform a
sanity check on the value when probing. This allows the other parts of
the driver to be simplified a bit.

Signed-off-by: Sander Vanheule <[email protected]>
Tested-by: Stijn Tintel <[email protected]>

target/linux/realtek/files-5.10/drivers/gpio/gpio-rtl8231.c

@@ -14,11 +14,13 @@
 
 #define USEC_TIMEOUT 5000
 
+#define RTL8231_SMI_BUS_ID_MAX			0x1F
+
 struct rtl8231_gpios {
 	struct gpio_chip gc;
 	struct device *dev;
 	u32 id;
-	int smi_bus_id;
+	u32 smi_bus_id;
 	u16 reg_shadow[0x20];
 	u32 reg_cached;
 	int ext_gpio_indrt_access;
@@ -30,13 +32,11 @@ extern struct rtl83xx_soc_info soc_info;
 static u32 rtl8231_read(struct rtl8231_gpios *gpios, u32 reg)
 {
 	u32 t = 0, n = 0;
-	u8 bus_id = gpios->smi_bus_id;
 
 	reg &= 0x1f;
-	bus_id &= 0x1f;
 
 	/* Calculate read register address */
-	t = (bus_id << 2) | (reg << 7);
+	t = (gpios->smi_bus_id << 2) | (reg << 7);
 
 	/* Set execution bit: cleared when operation completed */
 	t |= 1;
@@ -52,7 +52,8 @@ static u32 rtl8231_read(struct rtl8231_gpios *gpios, u32 reg)
 	if (n >= USEC_TIMEOUT)
 		return 0x80000000;
 	
-	pr_debug("%s: %x, %x, %x\n", __func__, bus_id, reg, (t & 0xffff0000) >> 16);
+	pr_debug("%s: %x, %x, %x\n", __func__, gpios->smi_bus_id,
+		reg, (t & 0xffff0000) >> 16);
 
 	return (t & 0xffff0000) >> 16;
 }
@@ -60,13 +61,11 @@ static u32 rtl8231_read(struct rtl8231_gpios *gpios, u32 reg)
 static int rtl8231_write(struct rtl8231_gpios *gpios, u32 reg, u32 data)
 {
 	u32 t = 0, n = 0;
-	u8 bus_id = gpios->smi_bus_id;
 
-	pr_debug("%s: %x, %x, %x\n", __func__, bus_id, reg, data);
+	pr_debug("%s: %x, %x, %x\n", __func__, gpios->smi_bus_id, reg, data);
 	reg &= 0x1f;
-	bus_id &= 0x1f;
 
-	t = (bus_id << 2) | (reg << 7) | (data << 16);
+	t = (gpios->smi_bus_id << 2) | (reg << 7) | (data << 16);
 	/* Set write bit */
 	t |= 2;
 
@@ -278,7 +277,6 @@ static int rtl8231_gpio_probe(struct platform_device *pdev)
 	struct device_node *np = dev->of_node;
 	struct rtl8231_gpios *gpios;
 	int err;
-	u32 indirect_bus_id;
 
 	pr_info("Probing RTL8231 GPIOs\n");
 
@@ -300,13 +298,14 @@ static int rtl8231_gpio_probe(struct platform_device *pdev)
 		gpios->ext_gpio_indrt_access = RTL839X_EXT_GPIO_INDRT_ACCESS;
 	}
 
-	/*
-	 * We use a default MDIO bus ID for the 8231 of 0, which can be overriden
-	 * by the indirect-access-bus-id property in the dts.
-	 */
-	gpios->smi_bus_id = 0;
-	of_property_read_u32(np, "indirect-access-bus-id", &indirect_bus_id);
-	gpios->smi_bus_id = indirect_bus_id;
+	err = of_property_read_u32(np, "indirect-access-bus-id", &gpios->smi_bus_id);
+	if (!err && gpios->smi_bus_id > RTL8231_SMI_BUS_ID_MAX)
+		err = -EINVAL;
+
+	if (err) {
+		dev_err(dev, "invalid or missing indirect-access-bus-id\n");
+		return err;
+	}
 
 	rtl8231_init(gpios);