1Cirrus EP93xx SPI controller driver HOWTO 2========================================= 3 4ep93xx_spi driver brings SPI master support for EP93xx SPI controller. Chip 5selects are implemented with GPIO lines. 6 7NOTE: If possible, don't use SFRMOUT (SFRM1) signal as a chip select. It will 8not work correctly (it cannot be controlled by software). Use GPIO lines 9instead. 10 11Sample configuration 12==================== 13 14Typically driver configuration is done in platform board files (the files under 15arch/arm/mach-ep93xx/*.c). In this example we configure MMC over SPI through 16this driver on TS-7260 board. You can adapt the code to suit your needs. 17 18This example uses EGPIO9 as SD/MMC card chip select (this is wired in DIO1 19header on the board). 20 21You need to select CONFIG_MMC_SPI to use mmc_spi driver. 22 23arch/arm/mach-ep93xx/ts72xx.c: 24 25... 26#include <linux/gpio.h> 27#include <linux/spi/spi.h> 28 29#include <mach/ep93xx_spi.h> 30 31/* this is our GPIO line used for chip select */ 32#define MMC_CHIP_SELECT_GPIO EP93XX_GPIO_LINE_EGPIO9 33 34static int ts72xx_mmc_spi_setup(struct spi_device *spi) 35{ 36 int err; 37 38 err = gpio_request(MMC_CHIP_SELECT_GPIO, spi->modalias); 39 if (err) 40 return err; 41 42 gpio_direction_output(MMC_CHIP_SELECT_GPIO, 1); 43 44 return 0; 45} 46 47static void ts72xx_mmc_spi_cleanup(struct spi_device *spi) 48{ 49 gpio_set_value(MMC_CHIP_SELECT_GPIO, 1); 50 gpio_direction_input(MMC_CHIP_SELECT_GPIO); 51 gpio_free(MMC_CHIP_SELECT_GPIO); 52} 53 54static void ts72xx_mmc_spi_cs_control(struct spi_device *spi, int value) 55{ 56 gpio_set_value(MMC_CHIP_SELECT_GPIO, value); 57} 58 59static struct ep93xx_spi_chip_ops ts72xx_mmc_spi_ops = { 60 .setup = ts72xx_mmc_spi_setup, 61 .cleanup = ts72xx_mmc_spi_cleanup, 62 .cs_control = ts72xx_mmc_spi_cs_control, 63}; 64 65static struct spi_board_info ts72xx_spi_devices[] __initdata = { 66 { 67 .modalias = "mmc_spi", 68 .controller_data = &ts72xx_mmc_spi_ops, 69 /* 70 * We use 10 MHz even though the maximum is 7.4 MHz. The driver 71 * will limit it automatically to max. frequency. 72 */ 73 .max_speed_hz = 10 * 1000 * 1000, 74 .bus_num = 0, 75 .chip_select = 0, 76 .mode = SPI_MODE_0, 77 }, 78}; 79 80static struct ep93xx_spi_info ts72xx_spi_info = { 81 .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices), 82}; 83 84static void __init ts72xx_init_machine(void) 85{ 86 ... 87 ep93xx_register_spi(&ts72xx_spi_info, ts72xx_spi_devices, 88 ARRAY_SIZE(ts72xx_spi_devices)); 89} 90 91The driver can use DMA for the transfers also. In this case ts72xx_spi_info 92becomes: 93 94static struct ep93xx_spi_info ts72xx_spi_info = { 95 .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices), 96 .use_dma = true; 97}; 98 99Note that CONFIG_EP93XX_DMA should be enabled as well. 100 101Thanks to 102========= 103Martin Guy, H. Hartley Sweeten and others who helped me during development of 104the driver. Simplemachines.it donated me a Sim.One board which I used testing 105the driver on EP9307. 106