drivers/spi/spi-clps711x.c

   1 /*
   2  *  CLPS711X SPI bus driver
   3  *
   4  *  Copyright (C) 2012-2016 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/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/regmap.h>
  19 #include <linux/mfd/syscon.h>
  20 #include <linux/mfd/syscon/clps711x.h>
  21 #include <linux/spi/spi.h>
  22
  23 #define DRIVER_NAME             "clps711x-spi"
  24
  25 #define SYNCIO_FRMLEN(x)        ((x) << 8)
  26 #define SYNCIO_TXFRMEN          (1 << 14)
  27
  28 struct spi_clps711x_data {
  29         void __iomem            *syncio;
  30         struct regmap           *syscon;
  31         struct clk              *spi_clk;
  32
  33         u8                      *tx_buf;
  34         u8                      *rx_buf;
  35         unsigned int            bpw;
  36         int                     len;
  37 };
  38
  39 static int spi_clps711x_setup(struct spi_device *spi)
  40 {
  41         if (!spi->controller_state) {
  42                 int ret;
  43
  44                 ret = devm_gpio_request(&spi->master->dev, spi->cs_gpio,
  45                                         dev_name(&spi->master->dev));
  46                 if (ret)
  47                         return ret;
  48
  49                 spi->controller_state = spi;
  50         }
  51
  52         /* We are expect that SPI-device is not selected */
  53         gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
  54
  55         return 0;
  56 }
  57
  58 static int spi_clps711x_prepare_message(struct spi_master *master,
  59                                         struct spi_message *msg)
  60 {
  61         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  62         struct spi_device *spi = msg->spi;
  63
  64         /* Setup mode for transfer */
  65         return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
  66                                   (spi->mode & SPI_CPHA) ?
  67                                   SYSCON3_ADCCKNSEN : 0);
  68 }
  69
  70 static int spi_clps711x_transfer_one(struct spi_master *master,
  71                                      struct spi_device *spi,
  72                                      struct spi_transfer *xfer)
  73 {
  74         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  75         u8 data;
  76
  77         clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
  78
  79         hw->len = xfer->len;
  80         hw->bpw = xfer->bits_per_word;
  81         hw->tx_buf = (u8 *)xfer->tx_buf;
  82         hw->rx_buf = (u8 *)xfer->rx_buf;
  83
  84         /* Initiate transfer */
  85         data = hw->tx_buf ? *hw->tx_buf++ : 0;
  86         writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
  87
  88         return 1;
  89 }
  90
  91 static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
  92 {
  93         struct spi_master *master = dev_id;
  94         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  95         u8 data;
  96
  97         /* Handle RX */
  98         data = readb(hw->syncio);
  99         if (hw->rx_buf)
 100                 *hw->rx_buf++ = data;
 101
 102         /* Handle TX */
 103         if (--hw->len > 0) {
 104                 data = hw->tx_buf ? *hw->tx_buf++ : 0;
 105                 writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
 106                        hw->syncio);
 107         } else
 108                 spi_finalize_current_transfer(master);
 109
 110         return IRQ_HANDLED;
 111 }
 112
 113 static int spi_clps711x_probe(struct platform_device *pdev)
 114 {
 115         struct spi_clps711x_data *hw;
 116         struct spi_master *master;
 117         struct resource *res;
 118         int irq, ret;
 119
 120         irq = platform_get_irq(pdev, 0);
 121         if (irq < 0)
 122                 return irq;
 123
 124         master = spi_alloc_master(&pdev->dev, sizeof(*hw));
 125         if (!master)
 126                 return -ENOMEM;
 127
 128         master->bus_num = -1;
 129         master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
 130         master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
 131         master->dev.of_node = pdev->dev.of_node;
 132         master->setup = spi_clps711x_setup;
 133         master->prepare_message = spi_clps711x_prepare_message;
 134         master->transfer_one = spi_clps711x_transfer_one;
 135
 136         hw = spi_master_get_devdata(master);
 137
 138         hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
 139         if (IS_ERR(hw->spi_clk)) {
 140                 ret = PTR_ERR(hw->spi_clk);
 141                 goto err_out;
 142         }
 143
 144         hw->syscon =
 145                 syscon_regmap_lookup_by_compatible("cirrus,ep7209-syscon3");
 146         if (IS_ERR(hw->syscon)) {
 147                 ret = PTR_ERR(hw->syscon);
 148                 goto err_out;
 149         }
 150
 151         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 152         hw->syncio = devm_ioremap_resource(&pdev->dev, res);
 153         if (IS_ERR(hw->syncio)) {
 154                 ret = PTR_ERR(hw->syncio);
 155                 goto err_out;
 156         }
 157
 158         /* Disable extended mode due hardware problems */
 159         regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
 160
 161         /* Clear possible pending interrupt */
 162         readl(hw->syncio);
 163
 164         ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
 165                                dev_name(&pdev->dev), master);
 166         if (ret)
 167                 goto err_out;
 168
 169         ret = devm_spi_register_master(&pdev->dev, master);
 170         if (!ret)
 171                 return 0;
 172
 173 err_out:
 174         spi_master_put(master);
 175
 176         return ret;
 177 }
 178
 179 static const struct of_device_id clps711x_spi_dt_ids[] = {
 180         { .compatible = "cirrus,ep7209-spi", },
 181         { }
 182 };
 183 MODULE_DEVICE_TABLE(of, clps711x_spi_dt_ids);
 184
 185 static struct platform_driver clps711x_spi_driver = {
 186         .driver = {
 187                 .name   = DRIVER_NAME,
 188                 .of_match_table = clps711x_spi_dt_ids,
 189         },
 190         .probe  = spi_clps711x_probe,
 191 };
 192 module_platform_driver(clps711x_spi_driver);
 193
 194 MODULE_LICENSE("GPL");
 195 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 196 MODULE_DESCRIPTION("CLPS711X SPI bus driver");
 197 MODULE_ALIAS("platform:" DRIVER_NAME);