pinctrl: bcm283x: Add GPIO pull-up/down control for BCM2835 and BCM2711

This patch adds support for configuring GPIO pull-up and pull-down
resistors in the BCM283x pinctrl driver. It implements the brcm,pull
device tree property to control pin bias settings.

The implementation follows the hardware-specific pull control
mechanisms:
- BCM2835: two-step GPPUD register sequence
- BCM2711: direct per-pin control registers

This enables device tree configurations to specify pull-up, pull-down,
or no bias for individual GPIO pins.

Tested on Raspberry Pi boards with both BCM2835 and BCM2711 SoCs.

Signed-off-by: Cibil Pankiras <cibil.pankiras@egym.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>

diff --git a/arch/arm/mach-bcm283x/include/mach/gpio.h b/arch/arm/mach-bcm283x/include/mach/gpio.h
index 4aeb48e..c54414a 100644 (file)
--- a/arch/arm/mach-bcm283x/include/mach/gpio.h
+++ b/arch/arm/mach-bcm283x/include/mach/gpio.h
@@ -26,6 +26,16 @@
 #define BCM2835_GPIO_FSEL_BANK(gpio)   (gpio / 10)
 #define BCM2835_GPIO_FSEL_SHIFT(gpio)  ((gpio % 10) * 3)
 
+/* BCM2835 GPIO Pull-up/down register offsets */
+#define BCM2835_GPPUD          37
+#define BCM2835_GPPUDCLK0      38
+
+/* BCM2711 GPIO Pull-up/down control */
+#define BCM2711_GPPUD_CNTRL_REG0       57
+#define BCM2711_PUD_REG_OFFSET(gpio)   ((gpio) / 16)
+#define BCM2711_PUD_REG_SHIFT(gpio)    (((gpio) % 16) * 2)
+#define BCM2711_PUD_2711_MASK          0x3
+
 struct bcm2835_gpio_regs {
        u32 gpfsel[6];
        u32 reserved1;

diff --git a/drivers/pinctrl/broadcom/pinctrl-bcm283x.c b/drivers/pinctrl/broadcom/pinctrl-bcm283x.c
index cf9350c..4ecc8ba 100644 (file)
--- a/drivers/pinctrl/broadcom/pinctrl-bcm283x.c
+++ b/drivers/pinctrl/broadcom/pinctrl-bcm283x.c
@@ -21,6 +21,8 @@
 #include <asm/system.h>
 #include <asm/io.h>
 #include <asm/gpio.h>
+#include <dt-bindings/pinctrl/bcm2835.h>
+#include <linux/delay.h>
 
 struct bcm283x_pinctrl_priv {
        u32 *base_reg;
@@ -54,7 +56,66 @@ static int bcm2835_gpio_get_func_id(struct udevice *dev, unsigned int gpio)
 }
 
 /*
- * bcm283x_pinctrl_set_state: configure pin functions.
+ * bcm2835_gpio_set_pull: Set GPIO pull-up/down resistor for BCM2835
+ * @dev: the pinctrl device
+ * @gpio: the GPIO pin number
+ * @pull: pull setting (BCM2835_PUD_OFF, BCM2835_PUD_DOWN, BCM2835_PUD_UP)
+ */
+static void bcm2835_gpio_set_pull(struct udevice *dev, unsigned int gpio, int pull)
+{
+       struct bcm283x_pinctrl_priv *priv = dev_get_priv(dev);
+       u32 bank = BCM2835_GPPUDCLK0 + BCM2835_GPIO_COMMON_BANK(gpio);
+       u32 bit = BCM2835_GPIO_COMMON_SHIFT(gpio);
+
+       /* Set required control signal */
+       writel(pull & 0x3, &priv->base_reg[BCM2835_GPPUD]);
+       udelay(1);
+
+       /* Clock the control signal into the GPIO pads */
+       writel(1 << bit, &priv->base_reg[bank]);
+       udelay(1);
+
+       /* Remove the control signal and clock */
+       writel(0, &priv->base_reg[BCM2835_GPPUD]);
+       writel(0, &priv->base_reg[bank]);
+}
+
+/*
+ * bcm2711_gpio_set_pull: Set GPIO pull-up/down resistor for BCM2711
+ * @dev: the pinctrl device
+ * @gpio: the GPIO pin number
+ * @pull: pull setting (BCM2835_PUD_OFF, BCM2835_PUD_DOWN, BCM2835_PUD_UP)
+ */
+static void bcm2711_gpio_set_pull(struct udevice *dev, unsigned int gpio, int pull)
+{
+       struct bcm283x_pinctrl_priv *priv = dev_get_priv(dev);
+       u32 reg_offset;
+       u32 bit_shift;
+       u32 pull_bits;
+
+       /* Findout which GPIO_PUP_PDN_CNTRL register to use */
+       reg_offset = BCM2711_GPPUD_CNTRL_REG0 + BCM2711_PUD_REG_OFFSET(gpio);
+
+       /* Findout the bit position */
+       bit_shift = BCM2711_PUD_REG_SHIFT(gpio);
+
+       /* Update the 2-bit field for this GPIO */
+       pull_bits = pull & BCM2711_PUD_2711_MASK;
+       clrsetbits_le32(&priv->base_reg[reg_offset],
+                       BCM2711_PUD_2711_MASK << bit_shift,
+                       pull_bits << bit_shift);
+}
+
+static void bcm283x_gpio_set_pull(struct udevice *dev, unsigned int gpio, int pull)
+{
+       if (device_is_compatible(dev, "brcm,bcm2835-gpio"))
+               bcm2835_gpio_set_pull(dev, gpio, pull);
+       else
+               bcm2711_gpio_set_pull(dev, gpio, pull);
+}
+
+/*
+ * bcm283x_pinctrl_set_state: configure pin functions and pull states.
  * @dev: the pinctrl device to be configured.
  * @config: the state to be configured.
  * @return: 0 in success
@@ -62,8 +123,10 @@ static int bcm2835_gpio_get_func_id(struct udevice *dev, unsigned int gpio)
 int bcm283x_pinctrl_set_state(struct udevice *dev, struct udevice *config)
 {
        u32 pin_arr[MAX_PINS_PER_BANK];
+       u32 pull_arr[MAX_PINS_PER_BANK];
        int function;
-       int i, len, pin_count = 0;
+       int i, len, pin_count = 0, pull_len = 0, pull_count = 0;
+       int pull_value;
 
        if (!dev_read_prop(config, "brcm,pins", &len) || !len ||
            len & 0x3 || dev_read_u32_array(config, "brcm,pins", pin_arr,
@@ -82,8 +145,44 @@ int bcm283x_pinctrl_set_state(struct udevice *dev, struct udevice *config)
                return -EINVAL;
        }
 
-       for (i = 0; i < pin_count; i++)
+       /* Check if brcm,pull property exists */
+       if (dev_read_prop(config, "brcm,pull", &pull_len) && pull_len > 0) {
+               if (pull_len & 0x3) {
+                       debug("Invalid pull array length for pinconfig %s (%d)\n",
+                             config->name, pull_len);
+                       return -EINVAL;
+               }
+
+               pull_count = pull_len / sizeof(u32);
+
+               if (pull_count != 1 && pull_count != pin_count) {
+                       debug("Pull array count (%d) must be 1 or match pin count (%d) for pinconfig %s\n",
+                             pull_count, pin_count, config->name);
+                       return -EINVAL;
+               }
+
+               if (dev_read_u32_array(config, "brcm,pull", pull_arr, pull_count)) {
+                       debug("Failed reading pull array for pinconfig %s\n", config->name);
+                       return -EINVAL;
+               }
+
+               /* Validate pull values */
+               for (i = 0; i < pull_count; i++) {
+                       if (pull_arr[i] > 2) {
+                               debug("Invalid pull value %d for pin %d in pinconfig %s\n",
+                                     pull_arr[i], pin_arr[i], config->name);
+                               return -EINVAL;
+                       }
+               }
+       }
+
+       for (i = 0; i < pin_count; i++) {
                bcm2835_gpio_set_func_id(dev, pin_arr[i], function);
+               if (pull_count > 0) {
+                       pull_value = (pull_count == 1) ? pull_arr[0] : pull_arr[i];
+                       bcm283x_gpio_set_pull(dev, pin_arr[i], pull_value);
+               }
+       }
 
        return 0;
 }