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/consumer.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_prepare_message(struct spi_master *master,
  40                                         struct spi_message *msg)
  41 {
  42         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  43         struct spi_device *spi = msg->spi;
  44
  45         /* Setup mode for transfer */
  46         return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
  47                                   (spi->mode & SPI_CPHA) ?
  48                                   SYSCON3_ADCCKNSEN : 0);
  49 }
  50
  51 static int spi_clps711x_transfer_one(struct spi_master *master,
  52                                      struct spi_device *spi,
  53                                      struct spi_transfer *xfer)
  54 {
  55         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  56         u8 data;
  57
  58         clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
  59
  60         hw->len = xfer->len;
  61         hw->bpw = xfer->bits_per_word;
  62         hw->tx_buf = (u8 *)xfer->tx_buf;
  63         hw->rx_buf = (u8 *)xfer->rx_buf;
  64
  65         /* Initiate transfer */
  66         data = hw->tx_buf ? *hw->tx_buf++ : 0;
  67         writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
  68
  69         return 1;
  70 }
  71
  72 static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
  73 {
  74         struct spi_master *master = dev_id;
  75         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  76         u8 data;
  77
  78         /* Handle RX */
  79         data = readb(hw->syncio);
  80         if (hw->rx_buf)
  81                 *hw->rx_buf++ = data;
  82
  83         /* Handle TX */
  84         if (--hw->len > 0) {
  85                 data = hw->tx_buf ? *hw->tx_buf++ : 0;
  86                 writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
  87                        hw->syncio);
  88         } else
  89                 spi_finalize_current_transfer(master);
  90
  91         return IRQ_HANDLED;
  92 }
  93
  94 static int spi_clps711x_probe(struct platform_device *pdev)
  95 {
  96         struct spi_clps711x_data *hw;
  97         struct spi_master *master;
  98         struct resource *res;
  99         int irq, ret;
 100
 101         irq = platform_get_irq(pdev, 0);
 102         if (irq < 0)
 103                 return irq;
 104
 105         master = spi_alloc_master(&pdev->dev, sizeof(*hw));
 106         if (!master)
 107                 return -ENOMEM;
 108
 109         master->use_gpio_descriptors = true;
 110         master->bus_num = -1;
 111         master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
 112         master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
 113         master->dev.of_node = pdev->dev.of_node;
 114         master->prepare_message = spi_clps711x_prepare_message;
 115         master->transfer_one = spi_clps711x_transfer_one;
 116
 117         hw = spi_master_get_devdata(master);
 118
 119         hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
 120         if (IS_ERR(hw->spi_clk)) {
 121                 ret = PTR_ERR(hw->spi_clk);
 122                 goto err_out;
 123         }
 124
 125         hw->syscon =
 126                 syscon_regmap_lookup_by_compatible("cirrus,ep7209-syscon3");
 127         if (IS_ERR(hw->syscon)) {
 128                 ret = PTR_ERR(hw->syscon);
 129                 goto err_out;
 130         }
 131
 132         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 133         hw->syncio = devm_ioremap_resource(&pdev->dev, res);
 134         if (IS_ERR(hw->syncio)) {
 135                 ret = PTR_ERR(hw->syncio);
 136                 goto err_out;
 137         }
 138
 139         /* Disable extended mode due hardware problems */
 140         regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
 141
 142         /* Clear possible pending interrupt */
 143         readl(hw->syncio);
 144
 145         ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
 146                                dev_name(&pdev->dev), master);
 147         if (ret)
 148                 goto err_out;
 149
 150         ret = devm_spi_register_master(&pdev->dev, master);
 151         if (!ret)
 152                 return 0;
 153
 154 err_out:
 155         spi_master_put(master);
 156
 157         return ret;
 158 }
 159
 160 static const struct of_device_id clps711x_spi_dt_ids[] = {
 161         { .compatible = "cirrus,ep7209-spi", },
 162         { }
 163 };
 164 MODULE_DEVICE_TABLE(of, clps711x_spi_dt_ids);
 165
 166 static struct platform_driver clps711x_spi_driver = {
 167         .driver = {
 168                 .name   = DRIVER_NAME,
 169                 .of_match_table = clps711x_spi_dt_ids,
 170         },
 171         .probe  = spi_clps711x_probe,
 172 };
 173 module_platform_driver(clps711x_spi_driver);
 174
 175 MODULE_LICENSE("GPL");
 176 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 177 MODULE_DESCRIPTION("CLPS711X SPI bus driver");
 178 MODULE_ALIAS("platform:" DRIVER_NAME);