全志v851s使用fbtft驱动0.96寸st7735屏分享

whycanservice2 LV 8

最近打算做个小玩意，需要驱动0.96寸的st7735，为此也踩了些坑，特此记录分享。
直接上配置吧：
1.电路图：

这里使用到spi0 以及 PD2 PD4 还有PH0 作为pwm0 没截图显示。
2.board.dts配置

&pio{
            .....
            	spi0_pins_a: spi0@0 {
            
            		allwinner,pins = "PC0", "PC2";
            
            		allwinner,pname = "spi0_sclk", "spi0_mosi";
            
            		allwinner,function = "spi0";
            
            		allwinner,muxsel = <4>;
            
            		allwinner,drive = <1>;
            
            		allwinner,pull = <0>;
            
            	};

            	spi0_pins_b: spi0@1 {
            
            		allwinner,pins = "PC1";
            
            		allwinner,pname = "spi0_cs0";
            
            		allwinner,function = "spi0";
            
            		allwinner,muxsel = <4>;
            
            		allwinner,drive = <1>;
            
            		allwinner,pull = <1>;   // only CS should be pulled up
            
            	};

            	spi0_pins_c: spi0@2 {
            
            		allwinner,pins = "PC0", "PC1", "PC2";
            
            		allwinner,function = "io_disabled";
            
            		allwinner,muxsel = <0xf>;
            
            		allwinner,drive = <1>;
            
            		allwinner,pull = <0>;
            
            	};

................
}；

以上为引脚配置，

&spi0 {
	clock-frequency = <100000000>;
	pinctrl-0 = <&spi0_pins_a &spi0_pins_b>;
	pinctrl-1 = <&spi0_pins_c>;
	pinctrl-names = "default", "sleep";
	spi0_cs_number = <1>;
	spi1_cs_bitmap = <1>;
	spi_slave_mode = <0>;
	spi_dbi_enable = <0>;
	status = "okay";

	st7789v@0 {
	    	status = "okay";
	    	compatible = "sitronix,st7735r";
		reg = <0>;
		spi-max-frequency = <32000000>;
		rotate = <90>;
		bgr;
		fps = <60>;
		buswidth = <8>;
		reset-gpios = <&pio PD 2 1 1 2 1>;
		dc-gpios = <&pio PD 4 1 1 2 0>;
		led-gpios = <&pio PH 0 1 1 2 1>;
		debug = <1>;
	    };
};

这里是spi0配置。

2.内核配置（可以选择关闭disp2，以及设备树删除disp lcd0 部分）
切记。一定要关闭uboot disp2 。

3.修改驱动代码
.../linux-4.9/drivers/staging/fbtft/fbtft-core.c 文件中
static int fbtft_request_one_gpio(struct fbtft_par *par, const char *name, int index, int *gpiop) 函数，修改后代码如下：

static int fbtft_request_one_gpio(struct fbtft_par *par,
				  const char *name, int index, int *gpiop)
{
	struct device *dev = par->info->device;
	struct device_node *node = dev->of_node;
	int gpio, flags, ret = 0;
	struct gpio_config gpio_of_flags;

	if (of_find_property(node, name, NULL)) {
		gpio = of_get_named_gpio_flags(node, name, index, (enum of_gpio_flags *)&gpio_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 = (gpio_of_flags.data & 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;
		}
		if (gpiop)
			*gpiop = gpio;
		fbtft_par_dbg(DEBUG_REQUEST_GPIOS, par, "%s: '%s' = GPIO%d\n",
							__func__, name, gpio);
	}
	return ret;
}

修改 .../linux-4.9/drivers/staging/fbtft/fb_st7735r.c 文件

主要修改一下驱动初始化代码列表：

static int default_init_sequence[] = {
	-1, MIPI_DCS_SOFT_RESET,
	-2, 150,                               /* delay */

	-1, MIPI_DCS_EXIT_SLEEP_MODE,
	-2, 500,                               /* delay */

	/* FRMCTR1 - frame rate control: normal mode
	 * frame rate = fosc / (1 x 2 + 40) * (LINE + 2C + 2D)
	 */
	-1, 0xB1, 0x05, 0x3C, 0x3C,

	/* FRMCTR2 - frame rate control: idle mode
	 * frame rate = fosc / (1 x 2 + 40) * (LINE + 2C + 2D)
	 */
	-1, 0xB2, 0x05, 0x3C, 0x3C,

	/* FRMCTR3 - frame rate control - partial mode
	 * dot inversion mode, line inversion mode
	 */
	-1, 0xB3, 0x05, 0x3C, 0x3C, 0x05, 0x3C, 0x3C,

	/* INVCTR - display inversion control
	 * no inversion
	 */
	-1, 0xB4, 0x03,

	/* PWCTR1 - Power Control
	 * -4.6V, AUTO mode
	 */
	-1, 0xC0, 0xAB, 0x0B, 0x04,

	/* PWCTR2 - Power Control
	 * VGH25 = 2.4C VGSEL = -10 VGH = 3 * AVDD
	 */
	-1, 0xC1, 0xC5,

	/* PWCTR3 - Power Control
	 * Opamp current small, Boost frequency
	 */
	-1, 0xC2, 0x0D, 0x00,

	/* PWCTR4 - Power Control
	 * BCLK/2, Opamp current small & Medium low
	 */
	-1, 0xC3, 0x8D, 0x6A,

	/* PWCTR5 - Power Control */
	-1, 0xC4, 0x8D, 0xEE,

	/* VMCTR1 - Power Control */
	-1, 0xC5, 0x0F,

	-1, 0x21, 

	-1, 0x3A, 0x05,

	-1, MIPI_DCS_SET_DISPLAY_ON,
	-2, 100,                               /* delay */

	-1, MIPI_DCS_ENTER_NORMAL_MODE,
	-2, 10,                               /* delay */

	/* end marker */
	-3
};

！！修改屏偏移

static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
{
	xs = xs + 1 ; xe = xe + 1 ;
	ys = ys + 26 ; ye = ye + 26;

	write_reg(par, MIPI_DCS_SET_COLUMN_ADDRESS,
		  xs >> 8, xs & 0xFF, xe >> 8, xe & 0xFF);

	write_reg(par, MIPI_DCS_SET_PAGE_ADDRESS,
		  ys >> 8, ys & 0xFF, ye >> 8, ye & 0xFF);

	write_reg(par, MIPI_DCS_WRITE_MEMORY_START);
}

修改屏参数：

static struct fbtft_display display = {
	.regwidth = 8,
	.width = 80,
	.height = 160,
	.init_sequence = default_init_sequence,
	.gamma_num = 2,
	.gamma_len = 16,
	.gamma = DEFAULT_GAMMA,
	.fbtftops = {
		.set_addr_win = set_addr_win,
		.set_var = set_var,
		.set_gamma = set_gamma,
	},
};

至此编译即可在小机端看到有fb0生成，屏幕点亮。
最后一图：

如有疑问，请跟贴。

frank LV 3

@whycanservice2 可以支持多个 tft 吗

mysteryli LV 7

@whycanservice2
老哥问两个问题
1.你的PH0做pwm调好了吗
2.屏幕会显示启动log嘛

frank LV 3

@frank 这改完 lcd0 不能用了啊