spi/ep93xx: implemented driver for Cirrus EP93xx SPI controller

This patch adds an SPI master driver for the Cirrus EP93xx SPI controller found
in EP93xx chips.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 95 insertions, 0 deletions

diff --git a/Documentation/spi/ep93xx_spi b/Documentation/spi/ep93xx_spi
new file mode 100644
index 000000000000..6325f5b48635
--- /dev/null
+++ b/Documentation/spi/ep93xx_spi
@@ -0,0 +1,95 @@
+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));
+}
+
+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.