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-Cirrus EP93xx SPI controller driver HOWTO
-=========================================
-
-ep93xx_spi driver brings SPI master support for EP93xx SPI controller. Chip
-selects are implemented with GPIO lines.
-
-NOTE: If possible, don't use SFRMOUT (SFRM1) signal as a chip select. It will
-not work correctly (it cannot be controlled by software). Use GPIO lines
-instead.
-
-Sample configuration
-====================
-
-Typically driver configuration is done in platform board files (the files under
-arch/arm/mach-ep93xx/*.c). In this example we configure MMC over SPI through
-this driver on TS-7260 board. You can adapt the code to suit your needs.
-
-This example uses EGPIO9 as SD/MMC card chip select (this is wired in DIO1
-header on the board).
-
-You need to select CONFIG_MMC_SPI to use mmc_spi driver.
-
-arch/arm/mach-ep93xx/ts72xx.c:
-
-...
-#include <linux/gpio.h>
-#include <linux/spi/spi.h>
-
-#include <mach/ep93xx_spi.h>
-
-/* this is our GPIO line used for chip select */
-#define MMC_CHIP_SELECT_GPIO EP93XX_GPIO_LINE_EGPIO9
-
-static int ts72xx_mmc_spi_setup(struct spi_device *spi)
-{
- int err;
-
- err = gpio_request(MMC_CHIP_SELECT_GPIO, spi->modalias);
- if (err)
- return err;
-
- gpio_direction_output(MMC_CHIP_SELECT_GPIO, 1);
-
- return 0;
-}
-
-static void ts72xx_mmc_spi_cleanup(struct spi_device *spi)
-{
- gpio_set_value(MMC_CHIP_SELECT_GPIO, 1);
- gpio_direction_input(MMC_CHIP_SELECT_GPIO);
- gpio_free(MMC_CHIP_SELECT_GPIO);
-}
-
-static void ts72xx_mmc_spi_cs_control(struct spi_device *spi, int value)
-{
- gpio_set_value(MMC_CHIP_SELECT_GPIO, value);
-}
-
-static struct ep93xx_spi_chip_ops ts72xx_mmc_spi_ops = {
- .setup = ts72xx_mmc_spi_setup,
- .cleanup = ts72xx_mmc_spi_cleanup,
- .cs_control = ts72xx_mmc_spi_cs_control,
-};
-
-static struct spi_board_info ts72xx_spi_devices[] __initdata = {
- {
- .modalias = "mmc_spi",
- .controller_data = &ts72xx_mmc_spi_ops,
- /*
- * We use 10 MHz even though the maximum is 7.4 MHz. The driver
- * will limit it automatically to max. frequency.
- */
- .max_speed_hz = 10 * 1000 * 1000,
- .bus_num = 0,
- .chip_select = 0,
- .mode = SPI_MODE_0,
- },
-};
-
-static struct ep93xx_spi_info ts72xx_spi_info = {
- .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices),
-};
-
-static void __init ts72xx_init_machine(void)
-{
- ...
- ep93xx_register_spi(&ts72xx_spi_info, ts72xx_spi_devices,
- ARRAY_SIZE(ts72xx_spi_devices));
-}
-
-The driver can use DMA for the transfers also. In this case ts72xx_spi_info
-becomes:
-
-static struct ep93xx_spi_info ts72xx_spi_info = {
- .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices),
- .use_dma = true;
-};
-
-Note that CONFIG_EP93XX_DMA should be enabled as well.
-
-Thanks to
-=========
-Martin Guy, H. Hartley Sweeten and others who helped me during development of
-the driver. Simplemachines.it donated me a Sim.One board which I used testing
-the driver on EP9307.