[PATCH] pinctrl: bcm283x: Add GPIO pull-up/down control for BCM2835 and BCM2711
Cibil Pankiras
cibil.pankiras at egym.com
Mon Nov 10 12:24:26 CET 2025
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 at egym.com>
---
arch/arm/mach-bcm283x/include/mach/gpio.h | 10 ++
drivers/pinctrl/broadcom/pinctrl-bcm283x.c | 102 ++++++++++++++++++++-
2 files changed, 109 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mach-bcm283x/include/mach/gpio.h b/arch/arm/mach-bcm283x/include/mach/gpio.h
index 4aeb48eeb20..c54414a012c 100644
--- 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 cf9350c151e..c588015905d 100644
--- 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 +123,9 @@ 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;
if (!dev_read_prop(config, "brcm,pins", &len) || !len ||
len & 0x3 || dev_read_u32_array(config, "brcm,pins", pin_arr,
@@ -82,8 +144,42 @@ 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 != pin_count) {
+ debug("Pull array count (%d) doesn't 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)
+ bcm283x_gpio_set_pull(dev, pin_arr[i], pull_arr[i]);
+ }
return 0;
}
--
2.43.0
--
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Geschäftsführende Direktoren:
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