tiny4412 设备树之LCD背光驱动（五）

开发板：tiny4412(1611)
内核：linux4.4
编译器： arm-none-linux-gnueabi-gcc （gcc version 4.8.3 20140320）
4412芯片gpx1 2接到双向电平转换器上：

LCD上有一个STM8单片机控制背光和传输触屏数据，通过一线协议。（触屏数据也可通过i2c直接读取）

关于一线背光驱动：
http://www.360doc.com/content/15/1031/21/6828497_509742486.shtml

---

devicetree

        backlight@139D0000{
                compatible         = "tiny4412,backlight_demo";
                reg = <0x139D0000 0x48>;
                tiny4412,backlight = <&gpx1 2 GPIO_ACTIVE_HIGH>;
                pinctrl-names = "backlight_out","backlight_in";
                pinctrl-0 = <&backlight_out>;
                pinctrl-1 = <&backlight_in>;
                interrupts = <0 40 0>;
                clocks = <&clock CLK_PWM>;
                clock-names = "timers";
        };

&pinctrl_1 {
        backlight_out: backlight_out{
                samsung,pins = "gpx1-2";
                samsung,pin-function = <1>;
                samsung,pin-pud = <0>;
                samsung,pin-drv = <0>;
        };
         backlight_in: backlight_in{
                samsung,pins = "gpx1-2";
                samsung,pin-function = <0>;
                samsung,pin-pud = <0>;
                samsung,pin-drv = <0>;
        };
};

---

驱动

//移植linux-3.5/drivers/input/touchscreen/tiny4412_1wire_host.c
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define dev_num 1

#define timer_debug printk("TCFG0:      %08x\n",timer->TCFG0);   \
            printk("TCFG1:      %08x\n",timer->TCFG1);   \
            printk("TCON:       %08x\n",timer->TCON);    \
            printk("TCNTB3:     %08x\n",timer->TCNTB3);  \
            printk("TCMPB3:     %08x\n",timer->TCMPB3);  \
            printk("TCNTO3:     %08x\n",timer->TCNTO3);  \
            printk("TINT_CSTAT: %08x\n",timer->TINT_CSTAT)

struct device *dev;
static struct pinctrl *pinctrl; 
static struct pinctrl_state *pinctrl_in;
static struct pinctrl_state *pinctrl_out;
static struct cdev gpj1_3_cdev;
static struct class *gpj_class;
static struct device *class_dev;
static int major;
static dev_t devid;
static int onewrite_pin;
static char devname[]="one_write";
//from tiny4412-1write-host.c
static DECLARE_WAIT_QUEUE_HEAD(bl_waitq);
static int bl_ready;
static unsigned char backlight_req = 0;
static unsigned char backlight_init_success;
enum {
    IDLE,
    START,
    REQUEST,
    WAITING,
    RESPONSE,
    STOPING,
} one_wire_status = IDLE;
//static int err_i = 0;

static volatile unsigned int io_bit_count;
static volatile unsigned int io_data;
static volatile unsigned char one_wire_request;

struct TIMER_BASEADDR{
unsigned int TCFG0;
unsigned int TCFG1;
unsigned int TCON; 
unsigned int TCNTB0; 
unsigned int TCMPB0; 
unsigned int TCNTO0; 
unsigned int TCNTB1;
unsigned int TCMPB1;
unsigned int TCNTO1; 
unsigned int TCNTB2; 
unsigned int TCMPB2; 
unsigned int TCNTO2; 
unsigned int TCNTB3; 
unsigned int TCMPB3; 
unsigned int TCNTO3; 
unsigned int TCNTB4; 
unsigned int TCNTO4; 
unsigned int TINT_CSTAT; 
};

volatile struct TIMER_BASEADDR *timer;

static inline void set_pin_up(void)
{
    /* TODO: */
#if 0
    unsigned long tmp;
    tmp = readl(S3C64XX_GPFPUD);
    tmp &= ~(3U <<30);
    tmp |= (2U << 30);
    writel(tmp, S3C64XX_GPFPUD);
#endif
}

static inline void set_pin_as_input(void)
{
    pinctrl_select_state(pinctrl,pinctrl_in);
}

static inline void set_pin_as_output(void)
{
    pinctrl_select_state(pinctrl,pinctrl_out);
}

static inline void set_pin_value(int v)
{
    if (v) {
        gpio_set_value(onewrite_pin, 1);
    } else {
        gpio_set_value(onewrite_pin, 0);
    }
}

static inline int get_pin_value(void)
{
    return gpio_get_value(onewrite_pin);
}


// CRC
//
static const unsigned char crc8_tab[] = {
0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15,
0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,
0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65,
0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,
0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5,
0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,
0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85,
0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,
0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2,
0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,
0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2,
0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,
0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32,
0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,
0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,
0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,
0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C,
0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,
0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC,
0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,
0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C,
0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,
0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C,
0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,
0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B,
0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,
0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B,
0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,
0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB,
0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB,
0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3,
};


#define crc8_init(crc) ((crc) = 0XACU)
#define crc8(crc, v) ( (crc) = crc8_tab[(crc) ^(v)])

// once a session complete
static unsigned total_received, total_error;
static unsigned last_req, last_res;

static inline void notify_bl_data(unsigned char a, unsigned char b, unsigned char c)
{
    bl_ready = 1;
    backlight_init_success = 1;
    wake_up_interruptible(&bl_waitq);
}

static void one_wire_session_complete(unsigned char req, unsigned int res)
{
    unsigned char crc;
    const unsigned char *p = (const unsigned char*)&res;
    total_received ++;

    last_res = res;

    crc8_init(crc);
    crc8(crc, p[3]);
    crc8(crc, p[2]);
    crc8(crc, p[1]);

    if (crc != p[0]) {
        // CRC dismatch
        if (total_received > 100) {
            total_error++;
        }
        return;
    }

    notify_bl_data(p[3], p[2], p[1]);

}

#define S3C2410_TCON_T3START      (1<<16)
// one-wire protocol core
static unsigned long TCNT_FOR_SAMPLE_BIT;
static unsigned long TCNT_FOR_FAST_LOOP;
static unsigned long TCNT_FOR_SLOW_LOOP;
#define SAMPLE_BPS 9600

#define SLOW_LOOP_FEQ 25
#define FAST_LOOP_FEQ 60
#define S3C2410_TCFG1_MUX3_MASK   (15<<12)

static int init_timer_for_1wire(struct clk *clk)
{
    //unsigned long tcfg1;
    unsigned long tcfg0;

    unsigned prescale1_value;

    unsigned long pclk;
    //struct clk *clk;

    // get pclk
    clk = clk_get(dev, "timers");
    if (IS_ERR(clk)) {
        printk("ERROR to get PCLK\n");
        return -EIO;
    }
    clk_enable(clk);

    pclk = clk_get_rate(clk);
    printk("PWM clock = %ld\n", pclk);

    // get prescaler
    tcfg0 = timer->TCFG0;
    // we use system prescaler value because timer 4 uses same one
    prescale1_value = (tcfg0 >> 8) & 0xFF;

    // calc the TCNT_FOR_SAMPLE_BIT, that is one of the goal
    TCNT_FOR_SAMPLE_BIT = pclk / (prescale1_value + 1) / SAMPLE_BPS - 1;
    TCNT_FOR_FAST_LOOP  = pclk / (prescale1_value + 1) / FAST_LOOP_FEQ - 1;
    TCNT_FOR_SLOW_LOOP  = pclk / (prescale1_value + 1) / SLOW_LOOP_FEQ - 1;

    // select timer 3, the 2rd goal
#if 0
    tcfg1 = timer->TCFG1;
    tcfg1 &= ~S3C2410_TCFG1_MUX3_MASK;
    timer->TCFG1=tcfg1;
#endif
    printk("TCNT_FOR_SAMPLE_BIT = %ld, TCFG1 = %08x\n",
            TCNT_FOR_SAMPLE_BIT,timer->TCFG1);
    return 0;
}


static inline void stop_timer_for_1wire(void)
{
    unsigned long tcon;
    tcon = timer->TCON;
    tcon &= ~S3C2410_TCON_T3START;
    timer->TCON=tcon;
}

static irqreturn_t timer_for_1wire_interrupt(int irq, void *dev_id)
{
    unsigned int tint;
    tint = timer->TINT_CSTAT;
    tint |= 0x100;
    timer->TINT_CSTAT=tint;

    io_bit_count--;
    switch(one_wire_status) {
    case START:
        if (io_bit_count == 0) {
            io_bit_count = 16;
            one_wire_status = REQUEST;
        }
        break;

    case REQUEST:
        // Send a bit
        set_pin_value(io_data & (1U << 31));
        io_data <<= 1;
        if (io_bit_count == 0) {
            io_bit_count = 2;
            one_wire_status = WAITING;
        }
        break;

    case WAITING:
        if (io_bit_count == 0) {
            io_bit_count = 32;
            one_wire_status = RESPONSE;
        }
        if (io_bit_count == 1) {
            set_pin_as_input();
            set_pin_value(1);
        }
        break;

    case RESPONSE:
        // Get a bit
        io_data = (io_data << 1) | get_pin_value();
        if (io_bit_count == 0) {
            io_bit_count = 2;
            one_wire_status = STOPING;
            set_pin_value(1);
            set_pin_as_output();
            one_wire_session_complete(one_wire_request, io_data);
        }
        break;

    case STOPING:
        if (io_bit_count == 0) {
            one_wire_status = IDLE;
            stop_timer_for_1wire();
        }
        break;

    default:
        stop_timer_for_1wire();
    }
    return IRQ_HANDLED;
}

#define S3C2410_TCON_T3RELOAD     (1<<19)
#define S3C2410_TCON_T3MANUALUPD  (1<<17)


static void start_one_wire_session(unsigned char req)
{
    unsigned int tcon;
    printk("backlight_write\n");
    one_wire_status = START;
    //gpio_set_value(one_write_pin, 1);
    //pinctrl_select_state(pctrl, pstate_out);
    set_pin_value(1);
    set_pin_as_output();

    // IDLE to START
    {
        unsigned char crc;
        crc8_init(crc);
        crc8(crc, req);
        io_data = (req << 8) + crc;
        io_data <<= 16;
    }
    io_bit_count = 1;
    set_pin_as_output();
    //pinctrl_select_state(pctrl, pstate_out);
    timer->TCNTB3 = 650;
    //init tranfer and start timer
    tcon = timer->TCON;
    tcon &= ~(0xF << 16);
    tcon |= (1 << 17);
    timer->TCON = tcon;
    tcon |= (1 << 16);
    tcon |= (1 << 19);
    tcon &= ~(1 << 17);
    timer->TCON = tcon;
    timer->TINT_CSTAT |= 0x08;
    //gpio_set_value(one_write_pin, 0);
    set_pin_value(0);
}

static int backlight_open(struct inode * inode, struct file * file){
    printk("%s enter.\n", __func__);



    return 0;
}


static ssize_t backlight_write(struct file *file, const char *buffer, size_t count, loff_t * ppos)
{
    int ret;
    char buf[4] = {0, 0, 0, 0};
    unsigned v;
    unsigned len;

    if (count == 0) {
        return -EINVAL;
    }

    if (count > sizeof buf - 1) {
        len = sizeof buf - 1;
    } else {
        len = count;
    }

    ret = copy_from_user(buf, buffer, len);
    if (ret) {
        return -EFAULT;
    }

    if (sscanf(buf, "%u", &v) != 1) {
        return -EINVAL;
    }

    if (v > 127) {
        v = 127;
    }

    bl_ready = 0;
    backlight_req = v + 0x80U;

    start_one_wire_session(backlight_req);

    ret = wait_event_interruptible_timeout(bl_waitq, bl_ready, HZ / 10);
    if (ret < 0) {
        return ret;
    }
    if (ret == 0) {
        return -ETIMEDOUT;
    }

    return count;
}

static int backlight_release(struct inode *inode, struct file *file){
    devm_gpio_free(dev,onewrite_pin);

    return 0;
}

static const struct file_operations gpj1_3_fops={  
    .owner   = THIS_MODULE,  
    .open     = backlight_open,   
    .write    = backlight_write,
    .release = backlight_release,  
};  

struct clk *clk=NULL;

static int pinctrl_probe(struct platform_device *pdev) {
    int error,ret;
    struct resource *res=NULL,*irq=NULL;

    dev = &pdev->dev;
    printk("%s enter.\n", __func__);

    if (!dev->of_node) {
            dev_err(dev, "no platform data.\n");
            goto err0;
    }
    /*request resource*/
    onewrite_pin=of_get_named_gpio(dev->of_node,"tiny4412,backlight",0);
    devm_gpio_request_one(dev, onewrite_pin,GPIOF_OUT_INIT_HIGH,"onewrite_pin");
    pinctrl=devm_pinctrl_get(dev);
    pinctrl_out=pinctrl_lookup_state(pinctrl,"backlight_out");
    pinctrl_in=pinctrl_lookup_state(pinctrl,"backlight_in");

    res=platform_get_resource(pdev,IORESOURCE_MEM,0);
    if(!res){
        dev_err(dev, "failed to get timer base mem resource\n");
        return -ENOMEM;
    }

    timer=devm_ioremap_resource(dev,res);
    if(timer<0){
        dev_err(dev, "failed to get timer base mem\n");
        return -ENOMEM;
    }
    printk("p:\ttimer: %p\n",timer);

    clk=devm_clk_get(dev,"timers");
    if(IS_ERR(clk)){
        dev_err(dev, "failed to get timer base clk\n");
        return PTR_ERR(clk);
        }   

    clk_prepare(clk);
    //timer_debug;

    timer->TCFG0  = 0xf00;
        timer->TCFG1  = 0x10004;
    error=init_timer_for_1wire(clk);

    //error = clk_enable((clk));
    if(error){
        printk("init timer error");
        return -1;
    }

    irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (irq == NULL){
            printk("platform_get_resource irq error\n");
        return -EINVAL;
        }
    ret = devm_request_irq(dev, irq->start, timer_for_1wire_interrupt , IRQF_TIMER, "backlight", NULL);
        if (ret)
        {
        dev_err(dev, "unable to request irq\n");
        return -EINVAL;
        }   

    timer->TINT_CSTAT=0x108;

    /*create cdev*/
    error=alloc_chrdev_region(&devid, 0, dev_num, "one_write");
    if(error){
        dev_err(dev, "alloc region failed.\n");
        goto err0;
    }
    major = MAJOR(devid);
    cdev_init(&gpj1_3_cdev, &gpj1_3_fops);
    cdev_add(&gpj1_3_cdev, MKDEV(major, 0), dev_num);
        gpj_class=class_create(THIS_MODULE,"gpj_1_3");  
        class_dev=device_create(gpj_class, NULL, devid, NULL, devname); 

    start_one_wire_session(0xf0);
    //printk("after first session\n");
    //timer_debug;

    start_one_wire_session(0xf0);
    //printk("after first session\n");
    //timer_debug;


    return 0;

err0:
        return -EINVAL;
}

static int pinctrl_remove(struct platform_device *pdev) {
    printk("%s enter.\n", __func__);
    clk_enable(clk);
    unregister_chrdev_region(devid,dev_num);
    cdev_del(&gpj1_3_cdev);
    device_destroy(gpj_class,MKDEV(major, 0));
    class_destroy(gpj_class);
    return 0;
}

static const struct of_device_id dt_ids[] = {
        { .compatible = "tiny4412,backlight_demo", },
        {},
};

MODULE_DEVICE_TABLE(of, dt_ids);

static struct platform_driver backlight_driver = {
    .driver        = {
         .name    = "one_write",
         .of_match_table    = of_match_ptr(dt_ids),
    },
     .probe        = pinctrl_probe,
     .remove        = pinctrl_remove,
};

static int backlight_init(void){
    int ret;

    printk("%s enter.\n", __func__); 
        ret = platform_driver_register(&backlight_driver);
        if (ret)
            printk(KERN_ERR "int demo: probe failed: %d\n", ret);

        return ret;
}

static void backlight_exit(void){

    printk("%s enter.\n", __func__);
    platform_driver_unregister(&backlight_driver);
}

module_init(backlight_init);
module_exit(backlight_exit);
MODULE_LICENSE("GPL");

---

效果：