记录为Linux配置spi屏幕（st7735s）

Posted 2021-05-08 qq_46604211

Linux配置spi屏幕（st7735s,使用我的板子需要增加底板）

ps：st7735s可用st7735r的驱动（但是我打算使用7789v的驱动来修改）参考老哥 的文章：https://www.bilibili.com/read/cv9947785

1.修改fb_st7789v.c文件

该文件在：linux-5.10/drivers/staging/fbtft

1.1 修改init_display函数：

static int init_display(struct fbtft_par *par)
{
	par->fbtftops.reset(par);//硬复位

	mdelay(50);
	write_reg(par,0x11);//软复位
	mdelay(100);
	//下面添加初始化函数write_reg 参数分别为：结构体指针，写命令，写数据....(后都为数据)
	//ST7735s Frame Rate
	write_reg(par,0xB1,0x05,0x3c,0x3c); 

	write_reg(par,0xB2,0x05,0x3c,0x3c);  

	write_reg(par,0xB3,0x05,0x3c,0x3c,0x05,0x3c,0x3c); 
 
	
	write_reg(par,0xB4,0x03); //Column inversion 
	
	//ST7735s Power Sequence
	write_reg(par,0xC0,0x28,0x08,0x04); 

	write_reg(par,0xC1,0xc0); 

	write_reg(par,0xC2,0x0d,0x00); 
	
	write_reg(par,0xC3,0x8d,0x2a); //VCOM 
	
	write_reg(par,0xc4,0x8d,0xee); //MX, MY, RGB mode  
	write_reg(par,0xc5,0x1a);
	write_reg(par,0x36,0xc0);
	//ST7735s Gamma Sequence
	write_reg(par,0xe0,0x04,0x22,0x07,0x0a,0x2e,0x30,0x25,0x2a,0x28,0x26,0x2e,0x3a,0x00,0x01,0x03,0x13); 

	write_reg(par,0xe1,0x04,0x16,0x06,0x0d,0x2d,0x26,0x23,0x27,0x27,0x25,0x2d,0x3b,0x00,0x01,0x04,0x13);  
	
	write_reg(par,0x3A,0x05); //65k mode  
	
	write_reg(par,0x29);//Display on
	mdelay(100);

	return 0;
}

1.2 修改struct fbtft_display display

修改屏幕高宽：

static struct fbtft_display display = {
	.regwidth = 8,
	.width = 128,//屏幕宽度
	.height = 160,//屏幕高度
	.gamma_num = 2,
	.gamma_len = 14,
	.gamma = HSD20_IPS_GAMMA,
	.fbtftops = {
		.init_display = init_display,
		.set_var = set_var,
		.set_gamma = set_gamma,
		.blank = blank,
	},
};

若使用st77335s需将set_gamma函数的for循环注释掉

2.修改fbtft-core.c文件（更新驱动的gpio申请函数）：

修改以下几个函数：

static int fbtft_request_one_gpio(struct fbtft_par *par,
				  const char *name, int index,
				  struct gpio_desc **gpiop)
{
	struct device *dev = par->info->device;
    struct device_node *node = dev->of_node;
    int gpio, flags, ret = 0;
    enum of_gpio_flags of_flags;
    if (of_find_property(node, name, NULL)) {
        gpio = of_get_named_gpio_flags(node, name, index, &of_flags);
        if (gpio == -ENOENT)
            return 0;
        if (gpio == -EPROBE_DEFER)
            return gpio;
        if (gpio < 0) {
            dev_err(dev,
                "failed to get '%s' from DT\\n", name);
            return gpio;
        }
         //active low translates to initially low
        flags = (of_flags & OF_GPIO_ACTIVE_LOW) ? GPIOF_OUT_INIT_LOW :
                            GPIOF_OUT_INIT_HIGH;
        ret = devm_gpio_request_one(dev, gpio, flags,
                        dev->driver->name);
        if (ret) {
            dev_err(dev,
                "gpio_request_one('%s'=%d) failed with %d\\n",
                name, gpio, ret);
            return ret;
        }

        *gpiop = gpio_to_desc(gpio);
        fbtft_par_dbg(DEBUG_REQUEST_GPios, par, "%s: '%s' = GPIO%d\\n",
                            __func__, name, gpio);
    }

    return ret;

}

static int fbtft_request_gpios(struct fbtft_par *par)
{
	int i;
    int ret;

    ret = fbtft_request_one_gpio(par, "reset-gpios", 0, &par->gpio.reset);
    if (ret)
        return ret;
    ret = fbtft_request_one_gpio(par, "dc-gpios", 0, &par->gpio.dc);
    if (ret)
        return ret;
    ret = fbtft_request_one_gpio(par, "rd-gpios", 0, &par->gpio.rd);
    if (ret)
        return ret;
    ret = fbtft_request_one_gpio(par, "wr-gpios", 0, &par->gpio.wr);
    if (ret)
        return ret;
    ret = fbtft_request_one_gpio(par, "cs-gpios", 0, &par->gpio.cs);
    if (ret)
        return ret;
    ret = fbtft_request_one_gpio(par, "latch-gpios", 0, &par->gpio.latch);
    if (ret)
        return ret;
    for (i = 0; i < 16; i++) {
        ret = fbtft_request_one_gpio(par, "db-gpios", i,
                         &par->gpio.db[i]);
        if (ret)
            return ret;
        ret = fbtft_request_one_gpio(par, "led-gpios", i,
                         &par->gpio.led[i]);
        if (ret)
            return ret;
        ret = fbtft_request_one_gpio(par, "aux-gpios", i,
                         &par->gpio.aux[i]);
        if (ret)
            return ret;
    }

    return 0;

}
static void fbtft_reset(struct fbtft_par *par)
{
    if (!par->gpio.reset)
        return;
    fbtft_par_dbg(DEBUG_RESET, par, "%s()\\n", __func__);
    gpiod_set_value_cansleep(par->gpio.reset, 1);
    msleep(10);
    gpiod_set_value_cansleep(par->gpio.reset, 0);
    msleep(200);
    gpiod_set_value_cansleep(par->gpio.reset, 1);
    msleep(10);
}

3.修改设备树：

添加 linux-5.10/arch/arm/boot/dts设备节点如下：

&spi0 {
        status ="okay";
    	st7789v@0 {
	       status ="okay";
               compatible = "sitronix,st7789v";
               reg = <0>;
               spi-max-frequency =<48000000>;        //SPI时钟50M
               rotate =<90>;                    //屏幕旋转90度
               spi-cpol;
               spi-cpha;
               rgb;                           //颜色格式RGB
               fps =<30>;                      //刷新30帧率
               buswidth =<8>;                   //总线宽度8
	       dc-gpios  =<&pio 1 6 GPIO_ACTIVE_LOW>;   //GPIOB6
	       reset-gpios=<&pio 1 5 GPIO_ACTIVE_LOW>;   //GPIOB5 暂时测试后面dc板子会改成pb4
               debug =<0>;                     //不开启调试
        };

3.配置linux内核：

make ARCH=arm menuconfig

配置如下：

ps:7735s也可直接修改fbtft-core.c文件，然后设备树的st7789v全改为st7783r，内核配置时选中ST7735R即可按照后面做。

4.编译内核：

	编译内核:
	make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j16
	make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j16 INSTALL_MOD_PATH=out modules
	make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j16 INSTALL_MOD_PATH=out modules_install
    编译设备树： make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- dtbs

将编译的内核zImage 和dtb文件替换tf卡内的文件即可。也可参考我的一片烧录的文章。

5.启动开发板

使用：

cat /dev/urandom > /dev/fb0 

看是否屏幕出现雪花点。（如果有就说明驱动上了）

6.添加控制台输出：

修改u-boot的bootargs参数进入u-boot时按任意键进入boot命令，输入：

setenv bootargs "console=tty0 console=ttyS0,115200 panic=5 rootwait root=/dev/mmcblk0p2 earlyprintk rw  vt.global_cursor_default=0"
saveenv

下一篇文章为使用板子播放BADAPPLE,有屏幕的地方就有BADAPPLE。