imx6用的是RS485，今天看看這個介面是怎麼初始化的。

首先在./arch/arm/mach-mx6/board-mx6q_sabresd.c裡找uart的相關資訊

在static void __init mx6_sabresd_board_init(void)肯定會有初始化的相關資訊

        gpio_request(SABRESD_EPDC_PWRSTAT, "uart2_en"); 申請gpio
	gpio_direction_output(SABRESD_EPDC_PWRSTAT, 1);  設定輸入輸出
	gpio_set_value(SABRESD_EPDC_PWRSTAT, 1);  設定初始電平

	gpio_request(SABRESD_EPDC_PWRCTRL0, "uart2_rts");
	gpio_direction_output(SABRESD_EPDC_PWRCTRL0, 1);
	gpio_set_value(SABRESD_EPDC_PWRCTRL0, 1);

	gpio_request(SABRESD_EPDC_PWRCTRL1, "uart3_en");
	gpio_direction_output(SABRESD_EPDC_PWRCTRL1, 1);
	gpio_set_value(SABRESD_EPDC_PWRCTRL1, 1);

	mx6q_sabresd_init_uart();
 

static const struct imxuart_platform_data mx6q_sd_uart3_data __initconst = {
.flags      = IMXUART_HAVE_RTSCTS,
.dma_req_rx = MX6Q_DMA_REQ_UART3_RX,
.dma_req_tx = MX6Q_DMA_REQ_UART3_TX,
};

static inline void mx6q_sabresd_init_uart(void)
{
	//imx6q_add_imx_uart(2, NULL);
	imx6q_add_imx_uart(0, NULL);
	imx6q_add_imx_uart(1, NULL);
	imx6q_add_imx_uart(2, &mx6q_sd_uart3_data);
	imx6q_add_imx_uart(3, NULL);
	imx6q_add_imx_uart(4, NULL);
}
 

struct platform_device *__init imx_add_imx_uart_1irq(
		const struct imx_imx_uart_1irq_data *data,
		const struct imxuart_platform_data *pdata)
{
	struct resource res[] = {
		{
			.start = data->iobase,
			.end = data->iobase + data->iosize - 1,
			.flags = IORESOURCE_MEM,
		}, {
			.start = data->irq,
			.end = data->irq,
			.flags = IORESOURCE_IRQ,
		},
	};

	return imx_add_platform_device("imx-uart", data->id, res, ARRAY_SIZE(res),
			pdata, sizeof(*pdata));
}
 

#ifdef CONFIG_SOC_IMX6Q
const struct imx_imx_uart_1irq_data imx6q_imx_uart_data[] __initconst = {
#define imx6q_imx_uart_data_entry(_id, _hwid) \
imx_imx_uart_1irq_data_entry(MX6Q, _id, _hwid, SZ_4K)
imx6q_imx_uart_data_entry(0, 1),
imx6q_imx_uart_data_entry(1, 2),
imx6q_imx_uart_data_entry(2, 3),
imx6q_imx_uart_data_entry(3, 4),
imx6q_imx_uart_data_entry(4, 5),
};

#define imx_imx_uart_1irq_data_entry(soc, _id, _hwid, _size)\
[_id] = { \
.id = _id, \
.iobase = soc ## _UART ## _hwid ## _BASE_ADDR,\
.iosize = _size,\
.irq = soc ## _INT_UART ## _hwid,\
}

到此為止，在linux系統中就存在了這個uart的pdate和resouce，等到驅動跑起來的時候傳入probe的引數就是從這裡來的