arch/arm/mach-u300/spi.c

   1 /*
   2  * arch/arm/mach-u300/spi.c
   3  *
   4  * Copyright (C) 2009 ST-Ericsson AB
   5  * License terms: GNU General Public License (GPL) version 2
   6  *
   7  * Author: Linus Walleij <linus.walleij@stericsson.com>
   8  */
   9 #include <linux/device.h>
  10 #include <linux/amba/bus.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/amba/pl022.h>
  13 #include <linux/err.h>
  14 #include "padmux.h"
  15
  16 /*
  17  * The following is for the actual devices on the SSP/SPI bus
  18  */
  19 #ifdef CONFIG_MACH_U300_SPIDUMMY
  20 static void select_dummy_chip(u32 chipselect)
  21 {
  22         pr_debug("CORE: %s called with CS=0x%x (%s)\n",
  23                  __func__,
  24                  chipselect,
  25                  chipselect ? "unselect chip" : "select chip");
  26         /*
  27          * Here you would write the chip select value to the GPIO pins if
  28          * this was a real chip (but this is a loopback dummy).
  29          */
  30 }
  31
  32 struct pl022_config_chip dummy_chip_info = {
  33         /* Nominally this is LOOPBACK_DISABLED, but this is our dummy chip! */
  34         .lbm = LOOPBACK_ENABLED,
  35         /*
  36          * available POLLING_TRANSFER and INTERRUPT_TRANSFER,
  37          * DMA_TRANSFER does not work
  38          */
  39         .com_mode = INTERRUPT_TRANSFER,
  40         .iface = SSP_INTERFACE_MOTOROLA_SPI,
  41         /* We can only act as master but SSP_SLAVE is possible in theory */
  42         .hierarchy = SSP_MASTER,
  43         /* 0 = drive TX even as slave, 1 = do not drive TX as slave */
  44         .slave_tx_disable = 0,
  45         /* LSB first */
  46         .endian_tx = SSP_TX_LSB,
  47         .endian_rx = SSP_RX_LSB,
  48         .data_size = SSP_DATA_BITS_8, /* used to be 12 in some default */
  49         .rx_lev_trig = SSP_RX_1_OR_MORE_ELEM,
  50         .tx_lev_trig = SSP_TX_1_OR_MORE_EMPTY_LOC,
  51         .clk_phase = SSP_CLK_SECOND_EDGE,
  52         .clk_pol = SSP_CLK_POL_IDLE_LOW,
  53         .ctrl_len = SSP_BITS_12,
  54         .wait_state = SSP_MWIRE_WAIT_ZERO,
  55         .duplex = SSP_MICROWIRE_CHANNEL_FULL_DUPLEX,
  56         /*
  57          * This is where you insert a call to a function to enable CS
  58          * (usually GPIO) for a certain chip.
  59          */
  60         .cs_control = select_dummy_chip,
  61 };
  62 #endif
  63
  64 static struct spi_board_info u300_spi_devices[] = {
  65 #ifdef CONFIG_MACH_U300_SPIDUMMY
  66         {
  67                 /* A dummy chip used for loopback tests */
  68                 .modalias       = "spi-dummy",
  69                 /* Really dummy, pass in additional chip config here */
  70                 .platform_data  = NULL,
  71                 /* This defines how the controller shall handle the device */
  72                 .controller_data = &dummy_chip_info,
  73                 /* .irq - no external IRQ routed from this device */
  74                 .max_speed_hz   = 1000000,
  75                 .bus_num        = 0, /* Only one bus on this chip */
  76                 .chip_select    = 0,
  77                 /* Means SPI_CS_HIGH, change if e.g low CS */
  78                 .mode           = 0,
  79         },
  80 #endif
  81 };
  82
  83 static struct pl022_ssp_controller ssp_platform_data = {
  84         /* If you have several SPI buses this varies, we have only bus 0 */
  85         .bus_id = 0,
  86         /* Set this to 1 when we think we got DMA working */
  87         .enable_dma = 0,
  88         /*
  89          * On the APP CPU GPIO 4, 5 and 6 are connected as generic
  90          * chip selects for SPI. (Same on U330, U335 and U365.)
  91          * TODO: make sure the GPIO driver can select these properly
  92          * and do padmuxing accordingly too.
  93          */
  94         .num_chipselect = 3,
  95 };
  96
  97
  98 void __init u300_spi_init(struct amba_device *adev)
  99 {
 100         struct pmx *pmx;
 101
 102         adev->dev.platform_data = &ssp_platform_data;
 103         /*
 104          * Setup padmuxing for SPI. Since this must always be
 105          * compiled into the kernel, pmx is never released.
 106          */
 107         pmx = pmx_get(&adev->dev, U300_APP_PMX_SPI_SETTING);
 108
 109         if (IS_ERR(pmx))
 110                 dev_warn(&adev->dev, "Could not get padmux handle\n");
 111         else {
 112                 int ret;
 113
 114                 ret = pmx_activate(&adev->dev, pmx);
 115                 if (IS_ERR_VALUE(ret))
 116                         dev_warn(&adev->dev, "Could not activate padmuxing\n");
 117         }
 118
 119 }
 120 void __init u300_spi_register_board_devices(void)
 121 {
 122         /* Register any SPI devices */
 123         spi_register_board_info(u300_spi_devices, ARRAY_SIZE(u300_spi_devices));
 124 }