root/drivers/leds/blink/leds-bcm63138.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
 */
#include <linux/bits.h>
#include <linux/cleanup.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#define BCM63138_MAX_LEDS                               32
#define BCM63138_MAX_BRIGHTNESS                         9

#define BCM63138_LED_BITS                               4                               /* how many bits control a single LED */
#define BCM63138_LED_MASK                               ((1 << BCM63138_LED_BITS) - 1)  /* 0xf */
#define BCM63138_LEDS_PER_REG                           (32 / BCM63138_LED_BITS)        /* 8 */

#define BCM63138_GLB_CTRL                               0x00
#define  BCM63138_GLB_CTRL_SERIAL_LED_DATA_PPOL         BIT(1)
#define  BCM63138_GLB_CTRL_SERIAL_LED_CLK_POL           BIT(2)
#define  BCM63138_GLB_CTRL_SERIAL_LED_EN_POL            BIT(3)
#define  BCM63138_GLB_CTRL_SERIAL_LED_MSB_FIRST         BIT(4)
#define BCM63138_MASK                                   0x04
#define BCM63138_HW_LED_EN                              0x08
#define BCM63138_SERIAL_LED_SHIFT_SEL                   0x0c
#define BCM63138_FLASH_RATE_CTRL1                       0x10
#define BCM63138_FLASH_RATE_CTRL2                       0x14
#define BCM63138_FLASH_RATE_CTRL3                       0x18
#define BCM63138_FLASH_RATE_CTRL4                       0x1c
#define BCM63138_BRIGHT_CTRL1                           0x20
#define BCM63138_BRIGHT_CTRL2                           0x24
#define BCM63138_BRIGHT_CTRL3                           0x28
#define BCM63138_BRIGHT_CTRL4                           0x2c
#define BCM63138_POWER_LED_CFG                          0x30
#define BCM63138_POWER_LUT_BASE0                        0x34 /* -> b0 */
#define BCM63138_HW_POLARITY                            0xb4
#define BCM63138_SW_DATA                                0xb8
#define BCM63138_SW_POLARITY                            0xbc
#define BCM63138_PARALLEL_LED_POLARITY                  0xc0
#define BCM63138_SERIAL_LED_POLARITY                    0xc4
#define BCM63138_HW_LED_STATUS                          0xc8
#define BCM63138_FLASH_CTRL_STATUS                      0xcc
#define BCM63138_FLASH_BRT_CTRL                         0xd0
#define BCM63138_FLASH_P_LED_OUT_STATUS                 0xd4
#define BCM63138_FLASH_S_LED_OUT_STATUS                 0xd8

struct bcm63138_leds {
        struct device *dev;
        void __iomem *base;
        spinlock_t lock;
};

struct bcm63138_led {
        struct bcm63138_leds *leds;
        struct led_classdev cdev;
        u32 pin;
        bool active_low;
};

/*
 * I/O access
 */

static void bcm63138_leds_write(struct bcm63138_leds *leds, unsigned int reg,
                                u32 data)
{
        writel(data, leds->base + reg);
}

static unsigned long bcm63138_leds_read(struct bcm63138_leds *leds,
                                        unsigned int reg)
{
        return readl(leds->base + reg);
}

static void bcm63138_leds_update_bits(struct bcm63138_leds *leds,
                                      unsigned int reg, u32 mask, u32 val)
{
        WARN_ON(val & ~mask);

        bcm63138_leds_write(leds, reg, (bcm63138_leds_read(leds, reg) & ~mask) | (val & mask));
}

/*
 * Helpers
 */

static void bcm63138_leds_set_flash_rate(struct bcm63138_leds *leds,
                                         struct bcm63138_led *led,
                                         u8 value)
{
        int reg_offset = (led->pin >> fls((BCM63138_LEDS_PER_REG - 1))) * 4;
        int shift = (led->pin & (BCM63138_LEDS_PER_REG - 1)) * BCM63138_LED_BITS;

        bcm63138_leds_update_bits(leds, BCM63138_FLASH_RATE_CTRL1 + reg_offset,
                                  BCM63138_LED_MASK << shift, value << shift);
}

static void bcm63138_leds_set_bright(struct bcm63138_leds *leds,
                                     struct bcm63138_led *led,
                                     u8 value)
{
        int reg_offset = (led->pin >> fls((BCM63138_LEDS_PER_REG - 1))) * 4;
        int shift = (led->pin & (BCM63138_LEDS_PER_REG - 1)) * BCM63138_LED_BITS;

        bcm63138_leds_update_bits(leds, BCM63138_BRIGHT_CTRL1 + reg_offset,
                                  BCM63138_LED_MASK << shift, value << shift);
}

static void bcm63138_leds_enable_led(struct bcm63138_leds *leds,
                                     struct bcm63138_led *led,
                                     enum led_brightness value)
{
        u32 bit = BIT(led->pin);

        bcm63138_leds_update_bits(leds, BCM63138_SW_DATA, bit, value ? bit : 0);
}

/*
 * API callbacks
 */

static void bcm63138_leds_brightness_set(struct led_classdev *led_cdev,
                                         enum led_brightness value)
{
        struct bcm63138_led *led = container_of(led_cdev, struct bcm63138_led, cdev);
        struct bcm63138_leds *leds = led->leds;

        guard(spinlock_irqsave)(&leds->lock);

        bcm63138_leds_enable_led(leds, led, value);
        if (!value)
                bcm63138_leds_set_flash_rate(leds, led, 0);
        else
                bcm63138_leds_set_bright(leds, led, value);
}

static int bcm63138_leds_blink_set(struct led_classdev *led_cdev,
                                   unsigned long *delay_on,
                                   unsigned long *delay_off)
{
        struct bcm63138_led *led = container_of(led_cdev, struct bcm63138_led, cdev);
        struct bcm63138_leds *leds = led->leds;
        u8 value;

        if (!*delay_on && !*delay_off) {
                *delay_on = 640;
                *delay_off = 640;
        }

        if (*delay_on != *delay_off) {
                dev_dbg(led_cdev->dev, "Blinking at unequal delays is not supported\n");
                return -EINVAL;
        }

        switch (*delay_on) {
        case 1152 ... 1408: /* 1280 ms ± 10% */
                value = 0x7;
                break;
        case 576 ... 704: /* 640 ms ± 10% */
                value = 0x6;
                break;
        case 288 ... 352: /* 320 ms ± 10% */
                value = 0x5;
                break;
        case 126 ... 154: /* 140 ms ± 10% */
                value = 0x4;
                break;
        case 59 ... 72: /* 65 ms ± 10% */
                value = 0x3;
                break;
        default:
                dev_dbg(led_cdev->dev, "Blinking delay value %lu is unsupported\n",
                        *delay_on);
                return -EINVAL;
        }

        guard(spinlock_irqsave)(&leds->lock);

        bcm63138_leds_enable_led(leds, led, BCM63138_MAX_BRIGHTNESS);
        bcm63138_leds_set_flash_rate(leds, led, value);

        return 0;
}

/*
 * LED driver
 */

static void bcm63138_leds_create_led(struct bcm63138_leds *leds,
                                     struct device_node *np)
{
        struct led_init_data init_data = {
                .fwnode = of_fwnode_handle(np),
        };
        struct device *dev = leds->dev;
        struct bcm63138_led *led;
        struct pinctrl *pinctrl;
        u32 bit;
        int err;

        led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
        if (!led) {
                dev_err(dev, "Failed to alloc LED\n");
                return;
        }

        led->leds = leds;

        if (of_property_read_u32(np, "reg", &led->pin)) {
                dev_err(dev, "Missing \"reg\" property in %pOF\n", np);
                goto err_free;
        }

        if (led->pin >= BCM63138_MAX_LEDS) {
                dev_err(dev, "Invalid \"reg\" value %d\n", led->pin);
                goto err_free;
        }

        led->active_low = of_property_read_bool(np, "active-low");

        led->cdev.max_brightness = BCM63138_MAX_BRIGHTNESS;
        led->cdev.brightness_set = bcm63138_leds_brightness_set;
        led->cdev.blink_set = bcm63138_leds_blink_set;

        err = devm_led_classdev_register_ext(dev, &led->cdev, &init_data);
        if (err) {
                dev_err(dev, "Failed to register LED %pOF: %d\n", np, err);
                goto err_free;
        }

        pinctrl = devm_pinctrl_get_select_default(led->cdev.dev);
        if (IS_ERR(pinctrl) && PTR_ERR(pinctrl) != -ENODEV) {
                dev_warn(led->cdev.dev, "Failed to select %pOF pinctrl: %ld\n",
                         np, PTR_ERR(pinctrl));
        }

        bit = BIT(led->pin);
        bcm63138_leds_update_bits(leds, BCM63138_PARALLEL_LED_POLARITY, bit,
                                  led->active_low ? 0 : bit);
        bcm63138_leds_update_bits(leds, BCM63138_HW_LED_EN, bit, 0);
        bcm63138_leds_set_flash_rate(leds, led, 0);
        bcm63138_leds_enable_led(leds, led, led->cdev.brightness);

        return;

err_free:
        devm_kfree(dev, led);
}

static int bcm63138_leds_probe(struct platform_device *pdev)
{
        struct device_node *np = dev_of_node(&pdev->dev);
        struct device *dev = &pdev->dev;
        struct bcm63138_leds *leds;
        u32 shift_bits;

        leds = devm_kzalloc(dev, sizeof(*leds), GFP_KERNEL);
        if (!leds)
                return -ENOMEM;

        leds->dev = dev;

        leds->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(leds->base))
                return PTR_ERR(leds->base);

        spin_lock_init(&leds->lock);

        /* If this property is not present, we use boot defaults */
        if (!of_property_read_u32(np, "brcm,serial-shift-bits", &shift_bits)) {
                bcm63138_leds_write(leds, BCM63138_SERIAL_LED_SHIFT_SEL,
                                    GENMASK(shift_bits - 1, 0));
        }

        bcm63138_leds_write(leds, BCM63138_GLB_CTRL,
                            BCM63138_GLB_CTRL_SERIAL_LED_DATA_PPOL |
                            BCM63138_GLB_CTRL_SERIAL_LED_EN_POL);
        bcm63138_leds_write(leds, BCM63138_HW_LED_EN, 0);
        bcm63138_leds_write(leds, BCM63138_SERIAL_LED_POLARITY, 0);
        bcm63138_leds_write(leds, BCM63138_PARALLEL_LED_POLARITY, 0);

        for_each_available_child_of_node_scoped(np, child) {
                bcm63138_leds_create_led(leds, child);
        }

        return 0;
}

static const struct of_device_id bcm63138_leds_of_match_table[] = {
        { .compatible = "brcm,bcm63138-leds", },
        { },
};

static struct platform_driver bcm63138_leds_driver = {
        .probe = bcm63138_leds_probe,
        .driver = {
                .name = "leds-bcm63xxx",
                .of_match_table = bcm63138_leds_of_match_table,
        },
};

module_platform_driver(bcm63138_leds_driver);

MODULE_AUTHOR("Rafał Miłecki");
MODULE_DESCRIPTION("Broadcom BCM63138 SoC LED driver");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(of, bcm63138_leds_of_match_table);