相關(guān)信息

硬件平臺(tái)：全志T507
系統(tǒng)版本：Android 10 / Linux 4.9.170
問(wèn)題描述：PF4 無(wú)法通過(guò)標(biāo)準(zhǔn)接口設(shè)置為中斷模式，而 PF1、PF2、PF3、PF5 正常可用。

分析過(guò)程

一開(kāi)始以為是引腳被其它驅(qū)動(dòng)占用引起，或者該引腳不具備中斷功能，經(jīng)過(guò)排查，已排除這兩種可能，因此通過(guò)從源碼分析來(lái)找問(wèn)題的根因。

以下是以 gpio_keys.c 驅(qū)動(dòng)為入口進(jìn)行分析：

// drivers/input/keyboard/gpio_keys.c
static int gpio_keys_setup_key(struct platform_device *pdev,
                struct input_dev *input,
                struct gpio_button_data *bdata,
                const struct gpio_keys_button *button)
{
    ......
    error = devm_request_any_context_irq(&pdev- >dev, bdata- >irq,
                         isr, irqflags, desc, bdata);
}

// kernel/irq/devres.c
int devm_request_any_context_irq(struct device *dev, unsigned int irq,
                  irq_handler_t handler, unsigned long irqflags,
                  const char *devname, void *dev_id)
{
    ......
    rc = request_any_context_irq(irq, handler, irqflags, devname, dev_id);
    if (rc < 0) {
        devres_free(dr);
        return rc;
    }
    ......
    return rc;
}

// kernel/irq/manage.c
int request_any_context_irq(unsigned int irq, irq_handler_t handler,
                unsigned long flags, const char *name, void *dev_id)
{
    ......
    ret = request_irq(irq, handler, flags, name, dev_id);
    return !ret ? IRQC_IS_HARDIRQ : ret;
}

// include/linux/interrupt.h
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
        const char *name, void *dev)
{
    return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}

// kernel/irq/manage.c
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
             irq_handler_t thread_fn, unsigned long irqflags,
             const char *devname, void *dev_id)
{
    ......
    chip_bus_lock(desc);
    retval = __setup_irq(irq, desc, action);
    chip_bus_sync_unlock(desc);
    ......
    return retval;
}

// kernel/irq/manage.c
static int __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
    ......

    if (!shared) {
        ret = irq_request_resources(desc);
        if (ret) {
            pr_err("Failed to request resources for %s (irq %d) on irqchip %sn",
                   new- >name, irq, desc- >irq_data.chip- >name);
            goto out_mask;
        }
        ......
    } 
    ......
}

// kernel/irq/manage.c
static int irq_request_resources(struct irq_desc *desc)
{
    struct irq_data *d = &desc- >irq_data;
    struct irq_chip *c = d- >chip;

    return c- >irq_request_resources ? c- >irq_request_resources(d) : 0;
}

// drivers/pinctrl/sunxi/pinctrl-sunxi.c
static struct irq_chip sunxi_pinctrl_edge_irq_chip = {
    .name        = "sunxi_pio_edge",
    .irq_ack    = sunxi_pinctrl_irq_ack,
    .irq_mask    = sunxi_pinctrl_irq_mask,
    .irq_unmask    = sunxi_pinctrl_irq_unmask,
    .irq_request_resources = sunxi_pinctrl_irq_request_resources,
    .irq_release_resources = sunxi_pinctrl_irq_release_resources,
    .irq_set_type    = sunxi_pinctrl_irq_set_type,
    .irq_set_wake    = sunxi_pinctrl_irq_set_wake,
};

// drivers/pinctrl/sunxi/pinctrl-sunxi.c
static int sunxi_pinctrl_irq_request_resources(struct irq_data *d)
{
    struct sunxi_pinctrl *pctl = irq_data_get_irq_chip_data(d);
    struct sunxi_desc_function *func;

    func = sunxi_pinctrl_desc_find_function_by_pin(pctl,
                    pctl- >irq_array[d- >hwirq], "irq");
    if (!func)
        return -EINVAL;

    /* Change muxing to INT mode */
    printk(KERN_EMERG"[lmx] irq:%d set int mode pin:%d d- >hwirq:%ld func- >muxval:%dn", d- >irq, pctl- >irq_array[d- >hwirq], d- >hwirq, func- >muxval);
    sunxi_pmx_set(pctl- >pctl_dev, pctl- >irq_array[d- >hwirq], func- >muxval);

    return 0;
}

// drivers/pinctrl/sunxi/pinctrl-sunxi.c
static void sunxi_pmx_set(struct pinctrl_dev *pctldev,
                 unsigned pin,
                 u8 config)
{
    struct sunxi_pinctrl *pctl = pinctrl_dev_get_drvdata(pctldev);
    unsigned long flags;
    u32 val, mask;

    raw_spin_lock_irqsave(&pctl- >lock, flags);
    pin -= pctl- >desc- >pin_base;
    val = readl(pctl- >membase + sunxi_mux_reg(pin));
    mask = MUX_PINS_MASK < < sunxi_mux_offset(pin);
    writel((val & ~mask) | config < < sunxi_mux_offset(pin),
        pctl- >membase + sunxi_mux_reg(pin));
    raw_spin_unlock_irqrestore(&pctl- >lock, flags);
}

無(wú)論有多復(fù)雜的代碼，最終都需要通過(guò)讀寫(xiě)寄存器的方式來(lái)實(shí)現(xiàn)控制芯片，而通過(guò)上述代碼分析，即可發(fā)現(xiàn) sunxi_pmx_set() 接口用于配置寄存器，是最底層的接口，可以通過(guò)打印輸出傳入的參數(shù)，來(lái)檢查是否有問(wèn)題。

PF3 打印輸出為：

[   10.683205] [lmx] irq:148 set int mode pin:163 d- >hwirq:131 func- >muxval:6

PF4 打印輸出為：

[   10.683557] [lmx] irq:149 set int mode pin:196 d- >hwirq:132 func- >muxval:6

這里就能看出很奇怪的地方，PF3 的引腳編號(hào)是 163，而 PF4 卻是 196，跨度很大。

通過(guò)以下指令查詢(xún) PF4 的正確引腳編號(hào)，也可以得知 196 引腳編號(hào)是哪一組：

mercury-demo:/ # cat /sys/kernel/debug/pinctrl/pio/pins
registered pins: 137
......
pin 160 (PF0)
pin 161 (PF1)
pin 162 (PF2)
pin 163 (PF3)
pin 164 (PF4)
pin 165 (PF5)
pin 166 (PF6)
......
pin 196 (PG4)
pin 197 (PG5)
......

確認(rèn) PF4 正確引腳編號(hào)是 164，而 196 對(duì)應(yīng)是 PG4，實(shí)際生效的是 PG4，通過(guò)以下指令即可確認(rèn)：

mercury-demo:/sys/kernel/debug/sunxi_pinctrl # echo PG4 > sunxi_pin
mercury-demo:/sys/kernel/debug/sunxi_pinctrl # cat *
pin[PG4] data: 1
pio
pin[PG4] dlevel: 1
pin[PG4] funciton: 6
NOMATCH
pin[PG4] pull: 1
PG4
pin[PG4] funciton: 6
pin[PG4] data: 1
pin[PG4] dlevel: 1
pin[PG4] pull: 1

根據(jù)代碼確定引腳編號(hào)來(lái)源于 pctl->irq_array 數(shù)組，通過(guò) pctl->irq_array 賦值的地方進(jìn)行打印輸出，是否一開(kāi)始就出錯(cuò)了：

// drivers/pinctrl/sunxi/pinctrl-sunxi.c
static int sunxi_pinctrl_build_state(struct platform_device *pdev)
{
    ......
    /* Count functions associated groups */
    for (i = 0; i  pctl- >desc- >npins; i++) {
        const struct sunxi_desc_pin *pin = pctl- >desc- >pins + i;
        struct sunxi_desc_function *func = pin- >functions;
        while (func- >name) {
            /* Create interrupt mapping while we're at it */
            if (!strcmp(func- >name, "irq")) {
                int irqnum = func- >irqnum + func- >irqbank * IRQ_PER_BANK;
                pctl- >irq_array[irqnum] = pin- >pin.number;
                printk(KERN_EMERG"[lmx] pctl- >irq_array[%d] = %d   (func- >irqnum:%d func- >irqbank:%d)n", irqnum, pin- >pin.number, func- >irqnum, func- >irqbank);
            }
            sunxi_pinctrl_add_function(pctl, func- >name);
            func++;
        }
    }
    ......
    return 0;
}
// drivers/pinctrl/sunxi/pinctrl-sunxi.h
#define IRQ_PER_BANK        32

可以發(fā)現(xiàn)，PF4(164)對(duì)應(yīng)的索引是 132，原本被正確賦值為 164，但又被覆蓋為 PG4(196)。
不難發(fā)現(xiàn)，出現(xiàn)覆蓋的原因是因?yàn)?PG4 的 func->irqbank 數(shù)值錯(cuò)誤(4)，導(dǎo)致索引下標(biāo)計(jì)算錯(cuò)誤。

根據(jù)前后文來(lái)看，func->irqbank 的正確數(shù)值應(yīng)該是 5，代入計(jì)算得到正確的值 164：
int irqnum(164) = func->irqnum(4) + func->irqbank(5) * IRQ_PER_BANK(32);

大概率硬件資源描述配置出錯(cuò)，通過(guò)搜索 irqbank 被賦值的方法，來(lái)定位描述配置出錯(cuò)的地方：

// drivers/pinctrl/sunxi/pinctrl-sunxi.h
#define SUNXI_FUNCTION_IRQ_BANK(_val, _bank, _irq)        
    {                            
        .name = "irq",                    
        .muxval = _val,                    
        .irqbank = _bank,                
        .irqnum = _irq,                    
    }

使用的是 SUNXI_FUNCTION_IRQ_BANK 宏，重點(diǎn)檢查第二個(gè)參數(shù)：

//    drivers/pinctrl/sunxi/pinctrl-sun50iw9p1.c
static const struct sunxi_desc_pin sun50iw9p1_pins[] = {
    ......
    SUNXI_PIN(SUNXI_PINCTRL_PIN(G, 3),
        SUNXI_FUNCTION(0x0, "gpio_in"),
        SUNXI_FUNCTION(0x1, "gpio_out"),
        SUNXI_FUNCTION(0x2, "sdc1"),        /* D1 */
        SUNXI_FUNCTION_IRQ_BANK(0x6, 5, 3),  /*  PG_EINT3    */
        SUNXI_FUNCTION(0x7, "io_disabled")),
    SUNXI_PIN(SUNXI_PINCTRL_PIN(G, 4),
        SUNXI_FUNCTION(0x0, "gpio_in"),
        SUNXI_FUNCTION(0x1, "gpio_out"),
        SUNXI_FUNCTION(0x2, "sdc1"),        /* D2 */
        // 可以發(fā)現(xiàn)第二個(gè)參數(shù)恰好是 4，根據(jù)分析結(jié)果，以及結(jié)合上下文，正確的應(yīng)該是 5
        SUNXI_FUNCTION_IRQ_BANK(0x6, 4, 4),  /*  PG_EINT4    */
        SUNXI_FUNCTION(0x7, "io_disabled")),
    SUNXI_PIN(SUNXI_PINCTRL_PIN(G, 5),
        SUNXI_FUNCTION(0x0, "gpio_in"),
        SUNXI_FUNCTION(0x1, "gpio_out"),
        SUNXI_FUNCTION(0x2, "sdc1"),        /* D3 */
        SUNXI_FUNCTION_IRQ_BANK(0x6, 5, 5),  /*  PG_EINT5    */
        SUNXI_FUNCTION(0x7, "io_disabled")),
    ......
};

修改之后的 pctl->irq_array 打印輸出正確：

進(jìn)行實(shí)測(cè)，PF4 已經(jīng)可以正常的被設(shè)置為中斷模式。

問(wèn)題總結(jié)

全志原廠提供的 SoCs pinctrl driver 中的 PG4 中斷信息描述錯(cuò)誤，導(dǎo)致覆蓋了 PF4 的引腳編號(hào)，因此只要修正 PG4 的描述信息，即可解決問(wèn)題。

這個(gè)問(wèn)題不僅僅會(huì)影響 PF4 無(wú)法使用，也會(huì)影響 PG4 引腳無(wú)法使用，從代碼來(lái)看，想要設(shè)置為 PG4 為中斷模式，實(shí)際修改的會(huì) PA0(0)。

--- a/longan/kernel/linux-4.9/drivers/pinctrl/sunxi/pinctrl-sun50iw9p1.c
+++ b/longan/kernel/linux-4.9/drivers/pinctrl/sunxi/pinctrl-sun50iw9p1.c
@@ -693,7 +693,7 @@
                SUNXI_FUNCTION(0x0, "gpio_in"),
                SUNXI_FUNCTION(0x1, "gpio_out"),
                SUNXI_FUNCTION(0x2, "sdc1"),            /* D2 */
-               SUNXI_FUNCTION_IRQ_BANK(0x6, 4, 4),  /*  PG_EINT4       */
+               SUNXI_FUNCTION_IRQ_BANK(0x6, 5, 4),  /*  PG_EINT4       */
                SUNXI_FUNCTION(0x7, "io_disabled")),
        SUNXI_PIN(SUNXI_PINCTRL_PIN(G, 5),
                SUNXI_FUNCTION(0x0, "gpio_in"),