davinci平台tsc2046触摸屏驱动移植

由于内核中已有ads7846的触摸屏驱动，而ads7846也兼容tsc2046，所以直接使用内核在中ads7846的驱动。

因为ads7846是通过spi总线进行读取数据的，所以首先要移植好spi总线驱动：
1.首先要进行管脚初始化，配置复用管脚寄存器。
//在ds850.c文件中：
static const struct mux_config da850_pins[] = {
    。。。。。。
    /*添加spi0的配置*/
    MUX_CFG(DA850, SPI0_CLK,    3,    0,    15,    1,    false)
    MUX_CFG(DA850, SPI0_ENA,    3,    4,    15,    1,    false)
    MUX_CFG(DA850, SPI0_SOMI,    3,    8,    15,    1,    false)
    MUX_CFG(DA850, SPI0_SIMO,    3,    12,    15,    1,    false)

    /*原来的配置注销掉
    MUX_CFG(DA850, MII_RXCLK,    3,    0,    15,    8,    false)
    MUX_CFG(DA850, MII_RXDV,    3,    4,    15,    8,    false)
    MUX_CFG(DA850, MII_RXER,    3,    8,    15,    8,    false)
    MUX_CFG(DA850, MII_CRS,        3,    12,    15,    8,    false)
    */
    。。。。。。
}

//在mux.h文件中添加
enum davinci_da850_index {
    。。。。。。
    /* spi0 function */
    DA850_SPI0_CLK,
    DA850_SPI0_ENA,
    DA850_SPI0_SOMI,
    DA850_SPI0_SIMO,
    。。。。。。
}

//在ds850.c文件中添加数组
const short da850_spi0_pins[] __initdata = {
    DA850_SPI0_CLK,DA850_SPI0_ENA,DA850_SPI0_SOMI,DA850_SPI0_SIMO,
    -1
};

//在da8xx.h中声明该数组
extern const short da850_spi0_pins[];

2.在board-da850-evm.c文件中添加
static int ads7846_get_pendown_state(void)
{
    return !gpio_get_value(DA850_PENIR_TS_GPIO);
}

static struct davinci_spi_platform_data da850evm_spi0_pdata = {
    .version    = SPI_VERSION_2,
    .num_chipselect = 1,
    .intr_line = 1,
};

struct ads7846_platform_data ads7846_config = {
     .model            = 7846,
    .x_min            = 150,
     .x_max            = 3830,
    .y_min            = 190,
     .y_max            = 3830,
    .vref_delay_usecs    = 100,
     .x_plate_ohms        = 900,
     .y_plate_ohms        = 900,
     .pressure_max        = 255,
    .debounce_max        = 10,
     .debounce_rep        = 1,
     .debounce_tol        = 50,
    .get_pendown_state    = ads7846_get_pendown_state,
    .keep_vref_on = 1,
    .wakeup         = true,
    .gpio_pendown         = DA850_PENIR_TS_GPIO,
};

static struct spi_board_info da850evm_spi_info[] = {
    {
        .modalias        = "m25p80",
        .platform_data    = &da850evm_spiflash_data,
        .controller_data    = &da850evm_spiflash_cfg,
        .mode            = SPI_MODE_0,
        .max_speed_hz        = 30000000,
        .bus_num        = 1,
        .chip_select        = 0,
    },

    {
        .modalias = "ads7846",//设备节点名，与xxx_driver中定义的名字相同
        .bus_num = 0,
        .chip_select = 0,
        .max_speed_hz = 1500000,
        .mode             = SPI_MODE_0,
        .irq = 128,//GPIO1[11]
        .platform_data = &ads7846_config,
  },
};

//在函数添加：
static __init void da850_evm_init(void)
{
    。。。。。
    da850evm_init_spi1(da850evm_spi_info, ARRAY_SIZE(da850evm_spi_info));//注册板级信息

    ret = davinci_cfg_reg_list(da850_spi0_pins);//管脚配置
    if (ret)
        pr_warning("da850_evm_init: spi0 mux setup failed: %d\n",    ret);
    da8xx_register_spi(0,&da850evm_spi0_pdata);//spi设备注册
    。。。。。。
}

3.make menuconfig时要添加spi驱动和触摸屏的驱动，编译即可。