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spi.c

/*
 * arch/arm/mach-u300/spi.c
 *
 * Copyright (C) 2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 *
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 */
#include <linux/device.h>
#include <linux/amba/bus.h>
#include <linux/spi/spi.h>
#include <linux/amba/pl022.h>
#include <linux/err.h>
#include "padmux.h"

/*
 * The following is for the actual devices on the SSP/SPI bus
 */
#ifdef CONFIG_MACH_U300_SPIDUMMY
static void select_dummy_chip(u32 chipselect)
{
      pr_debug("CORE: %s called with CS=0x%x (%s)\n",
             __func__,
             chipselect,
             chipselect ? "unselect chip" : "select chip");
      /*
       * Here you would write the chip select value to the GPIO pins if
       * this was a real chip (but this is a loopback dummy).
       */
}

struct pl022_config_chip dummy_chip_info = {
      /*
       * available POLLING_TRANSFER and INTERRUPT_TRANSFER,
       * DMA_TRANSFER does not work
       */
      .com_mode = INTERRUPT_TRANSFER,
      .iface = SSP_INTERFACE_MOTOROLA_SPI,
      /* We can only act as master but SSP_SLAVE is possible in theory */
      .hierarchy = SSP_MASTER,
      /* 0 = drive TX even as slave, 1 = do not drive TX as slave */
      .slave_tx_disable = 0,
      .rx_lev_trig = SSP_RX_1_OR_MORE_ELEM,
      .tx_lev_trig = SSP_TX_1_OR_MORE_EMPTY_LOC,
      .ctrl_len = SSP_BITS_12,
      .wait_state = SSP_MWIRE_WAIT_ZERO,
      .duplex = SSP_MICROWIRE_CHANNEL_FULL_DUPLEX,
      /*
       * This is where you insert a call to a function to enable CS
       * (usually GPIO) for a certain chip.
       */
      .cs_control = select_dummy_chip,
};
#endif

static struct spi_board_info u300_spi_devices[] = {
#ifdef CONFIG_MACH_U300_SPIDUMMY
      {
            /* A dummy chip used for loopback tests */
            .modalias       = "spi-dummy",
            /* Really dummy, pass in additional chip config here */
            .platform_data  = NULL,
            /* This defines how the controller shall handle the device */
            .controller_data = &dummy_chip_info,
            /* .irq - no external IRQ routed from this device */
            .max_speed_hz   = 1000000,
            .bus_num        = 0, /* Only one bus on this chip */
            .chip_select    = 0,
            /* Means SPI_CS_HIGH, change if e.g low CS */
            .mode           = SPI_MODE_1 | SPI_LOOP,
      },
#endif
};

static struct pl022_ssp_controller ssp_platform_data = {
      /* If you have several SPI buses this varies, we have only bus 0 */
      .bus_id = 0,
      /* Set this to 1 when we think we got DMA working */
      .enable_dma = 0,
      /*
       * On the APP CPU GPIO 4, 5 and 6 are connected as generic
       * chip selects for SPI. (Same on U330, U335 and U365.)
       * TODO: make sure the GPIO driver can select these properly
       * and do padmuxing accordingly too.
       */
      .num_chipselect = 3,
};


void __init u300_spi_init(struct amba_device *adev)
{
      struct pmx *pmx;

      adev->dev.platform_data = &ssp_platform_data;
      /*
       * Setup padmuxing for SPI. Since this must always be
       * compiled into the kernel, pmx is never released.
       */
      pmx = pmx_get(&adev->dev, U300_APP_PMX_SPI_SETTING);

      if (IS_ERR(pmx))
            dev_warn(&adev->dev, "Could not get padmux handle\n");
      else {
            int ret;

            ret = pmx_activate(&adev->dev, pmx);
            if (IS_ERR_VALUE(ret))
                  dev_warn(&adev->dev, "Could not activate padmuxing\n");
      }

}
void __init u300_spi_register_board_devices(void)
{
      /* Register any SPI devices */
      spi_register_board_info(u300_spi_devices, ARRAY_SIZE(u300_spi_devices));
}

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