基於tiny4412的Linux內核移植--- 中斷和GPIO學習（2）

作者

彭東林

pengdonglin137@163.com

平臺

tiny4412 ADK

Linux-4.4.4

u-boot使用的U-Boot 2010.12，是友善自帶的，爲支持設備樹和uImage做了稍許改動

概述

這篇博客以一個簡單的led燈實驗演示一下在含有設備樹、pinctrl時的gpio控制方法。

正文

我們以控制tiny4412上的LED1和LED2爲例，使用的GPIO是GPM4_0和GPM4_1對應的原理圖如下：

datasheet如下：

在samsung的pinctrl驅動中加一些調試用的log：

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 4e4c308..53fc268 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -753,6 +753,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
  */
 int gpiochip_generic_request(struct gpio_chip *chip, unsigned offset)
 {
+       printk("%s enter\n", __func__);
        return pinctrl_request_gpio(chip->base + offset);
 }
 EXPORT_SYMBOL_GPL(gpiochip_generic_request);
diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.c b/drivers/pinctrl/samsung/pinctrl-samsung.c
index 3f622cc..4f3bbe2 100644
--- a/drivers/pinctrl/samsung/pinctrl-samsung.c
+++ b/drivers/pinctrl/samsung/pinctrl-samsung.c
@@ -391,6 +391,7 @@ static void samsung_pinmux_setup(struct pinctrl_dev *pctldev, unsigned selector,
        if (enable)
                data |= func->val << shift;
        writel(data, reg + type->reg_offset[PINCFG_TYPE_FUNC]);
+       printk("%s: reg: 0x%x, value: 0x%x\n", __func__, reg + type->reg_offset[PINCFG_TYPE_FUNC], data);
 
        spin_unlock_irqrestore(&bank->slock, flags);
 }
@@ -447,6 +448,7 @@ static int samsung_pinconf_rw(struct pinctrl_dev *pctldev, unsigned int pin,
                data &= ~(mask << shift);
                data |= (cfg_value << shift);
                writel(data, reg_base + cfg_reg);
+               printk("%s: reg: 0x%x, value: 0x%x\n", __func__, reg_base + cfg_reg, data);
        } else {
                data >>= shift;
                data &= mask;
@@ -537,6 +539,7 @@ static void samsung_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
        if (value)
                data |= 1 << offset;
        writel(data, reg + type->reg_offset[PINCFG_TYPE_DAT]);
+       printk("%s: reg: 0x%x, value: 0x%x\n", __func__, reg + type->reg_offset[PINCFG_TYPE_DAT], data);
 
        spin_unlock_irqrestore(&bank->slock, flags);
 }
@@ -593,6 +596,7 @@ static int samsung_gpio_set_direction(struct gpio_chip *gc,
        if (!input)
                data |= FUNC_OUTPUT << shift;
        writel(data, reg);
+       printk("%s: reg: 0x%x, value: 0x%x\n", __func__, reg, data);
 
        spin_unlock_irqrestore(&bank->slock, flags);
 
@@ -622,6 +626,8 @@ static int samsung_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
        struct samsung_pin_bank *bank = gc_to_pin_bank(gc);
        unsigned int virq;
 
+       printk("%s enter.\n", __func__);
+
        if (!bank->irq_domain)
                return -ENXIO;

 將來在操作gpio的時候會回調到上面的這些函數。

在設備樹中添加相應的節點：

1. 首先把"gpio-leds"節點disable掉，否則會有衝突

2. 添加"tiny4412,gpio_demo"節點

3. 給pinctrl添加相關的pinmux節點

diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
index 610202a..0280935 100644
--- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
+++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
@@ -31,7 +31,7 @@
 #ifdef CONFIG_MMA7660_USE_I2C_GPIO
                i2c9 = &i2c_mma7660;
 #endif
-        };
+    };
 
        memory {
                reg = <0x40000000 0x40000000>;
@@ -39,7 +39,7 @@
 
        leds {
                compatible = "gpio-leds";
-
+        status = "disabled";
                led1 {
                        label = "led1";
                        gpios = <&gpm4 0 GPIO_ACTIVE_LOW>;
@@ -109,7 +109,7 @@
                   pinctrl-0 = <&pwm0_out>;
                   pinctrl-names = "default";
 #endif
-                   status = "disabled";
+           status = "disabled";
        };
 
 #ifdef CONFIG_MMA7660_USE_I2C_GPIO
@@ -136,6 +136,48 @@
                };
        };
 #endif
+
... ...45 +
+    gpio_demo: gpio_demo {
+               compatible = "tiny4412,gpio_demo";
+        reg = <0x110002e0 0x10>;
+        tiny4412,gpio = <&gpm4 0 GPIO_ACTIVE_HIGH &gpm4 1 GPIO_ACTIVE_HIGH>;
+        pinctrl-names = "default", "gpio_sleep", "gpio_active";
+        pinctrl-0 = <&led_gpio_default>;
+        pinctrl-1 = <&led_gpio_sleep>;
+        pinctrl-2 = <&led_gpio_active>;
+    };
+};
+
+&pinctrl_1 {
+    led_gpio_default: led_gpio_default {
+        samsung,pins = "gpm4-0", "gpm4-1";
+        samsung,pin-function = <1>;
+        samsung,pin-pud = <1>;
+        samsung,pin-drv = <2>;
+    };
+
+    led_gpio_sleep: led_gpio_sleep {
+        samsung,pins = "gpm4-0", "gpm4-1";
+        samsung,pin-function = <1>;
+        samsung,pin-pud = <0>;
+        samsung,pin-drv = <0>;
+    };
+
+    led_gpio_active: led_gpio_active {
+        samsung,pins = "gpm4-0", "gpm4-1";
+        samsung,pin-function = <1>;
+        samsung,pin-pud = <3>;
+        samsung,pin-drv = <3>;
+    };
 };
 
 &rtc {

 編寫對應的測試驅動程序：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_gpio.h>

typedef struct
{
    int gpio;
    int state;
    struct pinctrl *pctrl;
    struct pinctrl_state *sleep_pstate;
    struct pinctrl_state *active_pstate;
    char name[20];
} gpio_demo_data_t;

static u32 __iomem *base;
static u32 __iomem *cfg_reg;
static u32 __iomem *pud_reg;
static u32 __iomem *drv_reg;

static ssize_t gpio_demo_show(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    gpio_demo_data_t *data = dev_get_drvdata(dev);
    u32 config, pud, drv;

    config = readl(cfg_reg);
    pud = readl(pud_reg);
    drv = readl(drv_reg);

    return snprintf(buf, PAGE_SIZE, "gpio0: %s, gpio1: %s, cfg: 0x%x, pud: 0x%x, drv: 0x%x\n", data[0].state?"active":"sleep",
        data[1].state?"active":"sleep", config, pud, drv);
}

static ssize_t gpio_demo_store(struct device *dev,
    struct device_attribute *attr, const char *buf, size_t count)
{
    gpio_demo_data_t *data = dev_get_drvdata(dev);
    char state[10];
    int value = 0;

    if (sscanf(buf, "%s", state) != 1)
        return -EINVAL;
    if (strncmp(state, "active", strlen("active")) == 0) {  // 向gpio_demo中寫入active字符串
        pinctrl_select_state(data[0].pctrl, data[0].active_pstate);
        pinctrl_select_state(data[1].pctrl, data[1].active_pstate);
        data[0].state = 1;
        data[1].state = 1;
    } else if (strncmp(state, "sleep", strlen("sleep")) == 0) {  // 向gpio_demo中寫入sleep字符串
        pinctrl_select_state(data[0].pctrl, data[0].sleep_pstate);
        pinctrl_select_state(data[1].pctrl, data[1].sleep_pstate);
        data[0].state = 0;
        data[1].state = 0;
    } else if (sscanf(buf, "%d", &value)) { // 向gpio_demo中寫入數字可以控制GPM4_0(第0位)和GPM4_1(第1位)的高低電平
        if (value & (1 << 0))
            gpio_set_value(data[0].gpio, 1);
        else
            gpio_set_value(data[0].gpio, 0);

        if (value & (1 << 1))
            gpio_set_value(data[1].gpio, 1);
        else
            gpio_set_value(data[1].gpio, 0);
    }

    return count;
}

static DEVICE_ATTR(gpio_demo, 0644, gpio_demo_show,
    gpio_demo_store);

static int gpio_demo_probe(struct platform_device *pdev) {
    struct device *dev = &pdev->dev;
    int ret = 0;
    int i = 0;
    int gpio = -1;
    gpio_demo_data_t *data = NULL;
    struct resource *res = NULL;
    u32 config, pud, drv;

    printk("%s enter.\n", __func__);

    if (!dev->of_node) {
        dev_err(dev, "no platform data.\n");
        goto err1;
    }

    data = devm_kzalloc(dev, sizeof(*data)*2, GFP_KERNEL);
    if (!data) {
        dev_err(dev, "no memory.\n");
        goto err0;
    }

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    // 由於這部分內存空間在drivers/pinctrl/samsung/pinctrl-samsung.c中已經被申請，這裏再去申請會報錯，但是我們還是可以調用ioremap直接映射
#if 0
    base = devm_ioremap_resource(dev, res);
#else
    base = devm_ioremap(dev, res->start, res->end - res->start);
    printk("%s: remap: 0x%x ---> 0x%x to %p\n", __func__, res->start, res->end, base);
#endif
    if (IS_ERR(base)) {
        dev_err(dev, "remap failed.\n");
        devm_kfree(dev, data);
        return PTR_ERR(base);
    }

    cfg_reg = base;
    pud_reg = (u32 *)((u32)cfg_reg + 8);
    drv_reg = (u32 *)((u32)pud_reg + 4);

    for (i = 0; i < 2; i++) {
        gpio = of_get_named_gpio(dev->of_node,
            "tiny4412,gpio", i);    // 從設備樹中獲得gpio號
        if (gpio < 0) {
            dev_err(dev, "Looking up %s (%d) property in node %s failed %d\n",
                "tiny4412,gpio", i, dev->of_node->full_name, gpio);
            goto err2;
        }

        data[i].gpio = gpio;
        if (gpio_is_valid(gpio)) {
            sprintf(data[i].name, "tiny4412.led%d", i);
            ret = devm_gpio_request_one(dev, gpio, GPIOF_INIT_HIGH, data[i].name);  // 申請gpio資源
            if (ret < 0) {
                dev_err(dev, "request gpio %d failed.\n", gpio);
                goto err2;
            }
        }

        data[i].pctrl = devm_pinctrl_get(dev);   // 獲得pinctrl
        if (IS_ERR(data[i].pctrl)) {
            dev_err(dev, "pinctrl get failed.\n");
            devm_gpio_free(dev, gpio);
            goto err2;
        }

        data[i].sleep_pstate = pinctrl_lookup_state(data[i].pctrl, "gpio_sleep");   // 獲得'gpio_sleep'對應的配置
        if (IS_ERR(data[i].sleep_pstate)) {
            dev_err(dev, "look up sleep state failed.\n");
            devm_pinctrl_put(data[i].pctrl);
            devm_gpio_free(dev, gpio);
            goto err2;
        }

        data[i].active_pstate = pinctrl_lookup_state(data[i].pctrl, "gpio_active");   // 獲得'gpio_active'對應的配置
        if (IS_ERR(data[i].active_pstate)) {
            dev_err(dev, "look up sleep state failed.\n");
            devm_pinctrl_put(data[i].pctrl);
            devm_gpio_free(dev, gpio);
            goto err2;
        }
    }

    dev_set_drvdata(dev, data);
    // 這樣會在/sys/bus/platform/drivers/gpio_demo/110002e0.gpio_demo/下生成一個名爲gpio_demo的節點
    device_create_file(dev, &dev_attr_gpio_demo);

    config = readl(cfg_reg);
    pud = readl(pud_reg);
    drv = readl(drv_reg);
    printk("%s, default state: cfg: 0x%x, pud: 0x%x, drv: 0x%x\n", __func__, config, pud, drv);

    pinctrl_select_state(data[0].pctrl, data[0].active_pstate);   // 講GPM4_0設置爲active對應的配置
    pinctrl_select_state(data[1].pctrl, data[1].active_pstate);   // 講GPM4_1設置爲active對應的配置
    data[0].state = 1;
    data[1].state = 1;

    config = readl(cfg_reg);
    pud = readl(pud_reg);
    drv = readl(drv_reg);
    printk("%s, active state: cfg: 0x%x, pud: 0x%x, drv: 0x%x\n", __func__, config, pud, drv);

    return 0;

err2:
    devm_iounmap(dev, base);
err1:
    devm_kfree(dev, data);
err0:
    return -EINVAL;
}

static int gpio_demo_remove(struct platform_device *pdev)
{
    printk("%s enter.\n", __func__);
    device_remove_file(&pdev->dev, &dev_attr_gpio_demo);

    return 0;
}

static const struct of_device_id gpio_demo_dt_ids[] = {
    { .compatible = "tiny4412,gpio_demo", },
    {},
};

MODULE_DEVICE_TABLE(of, gpio_demo_dt_ids);

static struct platform_driver gpio_demo_driver = {
    .driver        = {
        .name    = "gpio_demo",
        .of_match_table    = of_match_ptr(gpio_demo_dt_ids),
    },
    .probe        = gpio_demo_probe,
    .remove        = gpio_demo_remove,
};

static int __init gpio_demo_init(void)
{
    int ret;

    ret = platform_driver_register(&gpio_demo_driver);
    if (ret)
        printk(KERN_ERR "int demo: probe failed: %d\n", ret);

    return ret;
}
module_init(gpio_demo_init);

static void __exit gpio_demo_exit(void)
{
    platform_driver_unregister(&gpio_demo_driver);
}
module_exit(gpio_demo_exit);

MODULE_LICENSE("GPL");

 使用新的設備樹鏡像啓動系統，加載上面的驅動：

[root@tiny4412 root]# cd /mnt/
[root@tiny4412 mnt]# ls
fdt                gpio_demo.ko       interrupt_demo.ko
[root@tiny4412 mnt]# insmod gpio_demo.ko 
[ 2353.713293] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2353.713451] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x555d
[ 2353.713633] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xe
[ 2353.713799] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2353.714409] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x5555
[ 2353.720404] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xa    // 在probe之前，會將這個gpio配置爲default指向的狀態
[ 2353.726129] gpio_demo_probe enter.
[ 2353.729197] gpio_demo_probe: remap: 0x110002e0 ---> 0x110002ef to f0a202e0
[ 2353.736304] gpiochip_generic_request enter
[ 2353.740113] samsung_gpio_set: reg: 0xf08a02e4, value: 0xf
[ 2353.745615] samsung_gpio_set_direction: reg: 0xf08a02e0, value: 0x1111   // 申請GPIO，並設置初始狀態
[ 2353.752264] gpiochip_generic_request enter
[ 2353.756144] samsung_gpio_set: reg: 0xf08a02e4, value: 0xf
[ 2353.761489] samsung_gpio_set_direction: reg: 0xf08a02e0, value: 0x1111
[ 2353.768047] gpio_demo_probe, default state: cfg: 0x1111, pud: 0x5555, drv: 0xa
[ 2353.775238] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2353.781199] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x5557
[ 2353.787003] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xb
[ 2353.792561] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2353.798549] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x555f
[ 2353.804707] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xf   // 將gpio設置爲active狀態
[ 2353.809868] gpio_demo_probe, active state: cfg: 0x1111, pud: 0x555f, drv: 0xf
[root@tiny4412 mnt]#  
[root@tiny4412 mnt]# cd /sys/bus/platform/drivers/gpio_demo/110002e0.gpio_demo/
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# ls
driver           gpio_demo        of_node          subsystem
driver_override  modalias         power            uevent
[root@tiny4412 110002e0.gpio_demo]# echo 0 > ./gpio_demo // 可以看到兩個LED燈都亮了
[ 2375.680666] samsung_gpio_set: reg: 0xf08a02e4, value: 0xe
[ 2375.680791] samsung_gpio_set: reg: 0xf08a02e4, value: 0xc
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo 3 > ./gpio_demo // 可以看到兩個LED燈都滅了
[ 2381.337016] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[ 2381.337135] samsung_gpio_set: reg: 0xf08a02e4, value: 0xf
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo 1 > ./gpio_demo // 可以看到兩個LED2亮了
[ 2392.969679] samsung_gpio_set: reg: 0xf08a02e4, value: 0xf
[ 2392.969798] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo 1 > ./gpio_demo // 可以看大，不會緩存上次的狀態
[ 2459.084622] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[ 2459.084744] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo 1 > ./gpio_demo 
[ 2478.405474] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[ 2478.405592] samsung_gpio_set: reg: 0xf08a02e4, value: 0xd
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo sleep > ./gpio_demo  // 設置爲sleep狀態，會緩存當前狀態，當前狀態已經是sleep了，再次設置sleep的時候，不會看到下面的log
[ 2939.212916] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2939.213045] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x555c
[ 2939.213160] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xc
[ 2939.213272] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2939.214008] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x5550
[ 2939.219955] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0x0
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# cat gpio_demo 
gpio0: sleep, gpio1: sleep, cfg: 0x1111, pud: 0x5550, drv: 0x0
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# echo active > ./gpio_demo   // 設置爲active狀態
[ 2950.581726] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2950.581855] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x5553
[ 2950.581968] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0x3
[ 2950.582078] samsung_pinmux_setup: reg: 0xf08a02e0, value: 0x1111
[ 2950.582821] samsung_pinconf_rw: reg: 0xf08a02e8, value: 0x555f
[ 2950.588734] samsung_pinconf_rw: reg: 0xf08a02ec, value: 0xf
[root@tiny4412 110002e0.gpio_demo]# 
[root@tiny4412 110002e0.gpio_demo]# cat gpio_demo 
gpio0: active, gpio1: active, cfg: 0x1111, pud: 0x555f, drv: 0xf
[root@tiny4412 110002e0.gpio_demo]# 

對應寄存器手冊和設備樹的屬性，可以理解上面的log。

 

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