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

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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>
This commit is contained in:
Cibil Pankiras
2025-11-14 00:45:32 +01:00
committed by Peter Robinson
parent 46e0ac55e5
commit 2c39d975f8
2 changed files with 112 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
arch/arm/mach-bcm283x/include/mach/gpio.h
View File

@@ -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;

105
drivers/pinctrl/broadcom/pinctrl-bcm283x.c
View File

@@ -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;
}