drivers/spi/spi-clps711x.c

   1 /*
   2  *  CLPS711X SPI bus driver
   3  *
   4  *  Copyright (C) 2012-2014 Alexander Shiyan <shc_work@mail.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/io.h>
  13 #include <linux/clk.h>
  14 #include <linux/gpio.h>
  15 #include <linux/delay.h>
  16 #include <linux/module.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/regmap.h>
  20 #include <linux/mfd/syscon.h>
  21 #include <linux/mfd/syscon/clps711x.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/platform_data/spi-clps711x.h>
  24
  25 #define DRIVER_NAME     "spi-clps711x"
  26
  27 #define SYNCIO_FRMLEN(x)        ((x) << 8)
  28 #define SYNCIO_TXFRMEN          (1 << 14)
  29
  30 struct spi_clps711x_data {
  31         void __iomem            *syncio;
  32         struct regmap           *syscon;
  33         struct clk              *spi_clk;
  34
  35         u8                      *tx_buf;
  36         u8                      *rx_buf;
  37         unsigned int            bpw;
  38         int                     len;
  39 };
  40
  41 static int spi_clps711x_setup(struct spi_device *spi)
  42 {
  43         /* We are expect that SPI-device is not selected */
  44         gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
  45
  46         return 0;
  47 }
  48
  49 static int spi_clps711x_prepare_message(struct spi_master *master,
  50                                         struct spi_message *msg)
  51 {
  52         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  53         struct spi_device *spi = msg->spi;
  54
  55         /* Setup mode for transfer */
  56         return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
  57                                   (spi->mode & SPI_CPHA) ?
  58                                   SYSCON3_ADCCKNSEN : 0);
  59 }
  60
  61 static int spi_clps711x_transfer_one(struct spi_master *master,
  62                                      struct spi_device *spi,
  63                                      struct spi_transfer *xfer)
  64 {
  65         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  66         u8 data;
  67
  68         clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
  69
  70         hw->len = xfer->len;
  71         hw->bpw = xfer->bits_per_word;
  72         hw->tx_buf = (u8 *)xfer->tx_buf;
  73         hw->rx_buf = (u8 *)xfer->rx_buf;
  74
  75         /* Initiate transfer */
  76         data = hw->tx_buf ? *hw->tx_buf++ : 0;
  77         writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
  78
  79         return 1;
  80 }
  81
  82 static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
  83 {
  84         struct spi_master *master = dev_id;
  85         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  86         u8 data;
  87
  88         /* Handle RX */
  89         data = readb(hw->syncio);
  90         if (hw->rx_buf)
  91                 *hw->rx_buf++ = data;
  92
  93         /* Handle TX */
  94         if (--hw->len > 0) {
  95                 data = hw->tx_buf ? *hw->tx_buf++ : 0;
  96                 writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
  97                        hw->syncio);
  98         } else
  99                 spi_finalize_current_transfer(master);
 100
 101         return IRQ_HANDLED;
 102 }
 103
 104 static int spi_clps711x_probe(struct platform_device *pdev)
 105 {
 106         struct spi_clps711x_data *hw;
 107         struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
 108         struct spi_master *master;
 109         struct resource *res;
 110         int i, irq, ret;
 111
 112         if (!pdata) {
 113                 dev_err(&pdev->dev, "No platform data supplied\n");
 114                 return -EINVAL;
 115         }
 116
 117         if (pdata->num_chipselect < 1) {
 118                 dev_err(&pdev->dev, "At least one CS must be defined\n");
 119                 return -EINVAL;
 120         }
 121
 122         irq = platform_get_irq(pdev, 0);
 123         if (irq < 0)
 124                 return irq;
 125
 126         master = spi_alloc_master(&pdev->dev, sizeof(*hw));
 127         if (!master)
 128                 return -ENOMEM;
 129
 130         master->cs_gpios = devm_kzalloc(&pdev->dev, sizeof(int) *
 131                                         pdata->num_chipselect, GFP_KERNEL);
 132         if (!master->cs_gpios) {
 133                 ret = -ENOMEM;
 134                 goto err_out;
 135         }
 136
 137         master->bus_num = pdev->id;
 138         master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
 139         master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
 140         master->num_chipselect = pdata->num_chipselect;
 141         master->setup = spi_clps711x_setup;
 142         master->prepare_message = spi_clps711x_prepare_message;
 143         master->transfer_one = spi_clps711x_transfer_one;
 144
 145         hw = spi_master_get_devdata(master);
 146
 147         for (i = 0; i < master->num_chipselect; i++) {
 148                 master->cs_gpios[i] = pdata->chipselect[i];
 149                 ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
 150                                         DRIVER_NAME);
 151                 if (ret) {
 152                         dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
 153                         goto err_out;
 154                 }
 155         }
 156
 157         hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
 158         if (IS_ERR(hw->spi_clk)) {
 159                 ret = PTR_ERR(hw->spi_clk);
 160                 goto err_out;
 161         }
 162
 163         hw->syscon = syscon_regmap_lookup_by_pdevname("syscon.3");
 164         if (IS_ERR(hw->syscon)) {
 165                 ret = PTR_ERR(hw->syscon);
 166                 goto err_out;
 167         }
 168
 169         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 170         hw->syncio = devm_ioremap_resource(&pdev->dev, res);
 171         if (IS_ERR(hw->syncio)) {
 172                 ret = PTR_ERR(hw->syncio);
 173                 goto err_out;
 174         }
 175
 176         /* Disable extended mode due hardware problems */
 177         regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
 178
 179         /* Clear possible pending interrupt */
 180         readl(hw->syncio);
 181
 182         ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
 183                                dev_name(&pdev->dev), master);
 184         if (ret)
 185                 goto err_out;
 186
 187         ret = devm_spi_register_master(&pdev->dev, master);
 188         if (!ret) {
 189                 dev_info(&pdev->dev,
 190                          "SPI bus driver initialized. Master clock %u Hz\n",
 191                          master->max_speed_hz);
 192                 return 0;
 193         }
 194
 195         dev_err(&pdev->dev, "Failed to register master\n");
 196
 197 err_out:
 198         spi_master_put(master);
 199
 200         return ret;
 201 }
 202
 203 static struct platform_driver clps711x_spi_driver = {
 204         .driver = {
 205                 .name   = DRIVER_NAME,
 206                 .owner  = THIS_MODULE,
 207         },
 208         .probe  = spi_clps711x_probe,
 209 };
 210 module_platform_driver(clps711x_spi_driver);
 211
 212 MODULE_LICENSE("GPL");
 213 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 214 MODULE_DESCRIPTION("CLPS711X SPI bus driver");
 215 MODULE_ALIAS("platform:" DRIVER_NAME);