linux/drivers/spi/spi-clps711x.c
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   1/*
   2 *  CLPS711X SPI bus driver
   3 *
   4 *  Copyright (C) 2012 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/init.h>
  15#include <linux/gpio.h>
  16#include <linux/delay.h>
  17#include <linux/module.h>
  18#include <linux/interrupt.h>
  19#include <linux/platform_device.h>
  20#include <linux/spi/spi.h>
  21#include <linux/platform_data/spi-clps711x.h>
  22
  23#include <mach/hardware.h>
  24
  25#define DRIVER_NAME     "spi-clps711x"
  26
  27struct spi_clps711x_data {
  28        struct completion       done;
  29
  30        struct clk              *spi_clk;
  31        u32                     max_speed_hz;
  32
  33        u8                      *tx_buf;
  34        u8                      *rx_buf;
  35        int                     count;
  36        int                     len;
  37
  38        int                     chipselect[0];
  39};
  40
  41static int spi_clps711x_setup(struct spi_device *spi)
  42{
  43        struct spi_clps711x_data *hw = spi_master_get_devdata(spi->master);
  44
  45        if (spi->bits_per_word != 8) {
  46                dev_err(&spi->dev, "Unsupported master bus width %i\n",
  47                        spi->bits_per_word);
  48                return -EINVAL;
  49        }
  50
  51        /* We are expect that SPI-device is not selected */
  52        gpio_direction_output(hw->chipselect[spi->chip_select],
  53                              !(spi->mode & SPI_CS_HIGH));
  54
  55        return 0;
  56}
  57
  58static void spi_clps711x_setup_mode(struct spi_device *spi)
  59{
  60        /* Setup edge for transfer */
  61        if (spi->mode & SPI_CPHA)
  62                clps_writew(clps_readw(SYSCON3) | SYSCON3_ADCCKNSEN, SYSCON3);
  63        else
  64                clps_writew(clps_readw(SYSCON3) & ~SYSCON3_ADCCKNSEN, SYSCON3);
  65}
  66
  67static int spi_clps711x_setup_xfer(struct spi_device *spi,
  68                                   struct spi_transfer *xfer)
  69{
  70        u32 speed = xfer->speed_hz ? : spi->max_speed_hz;
  71        u8 bpw = xfer->bits_per_word;
  72        struct spi_clps711x_data *hw = spi_master_get_devdata(spi->master);
  73
  74        if (bpw != 8) {
  75                dev_err(&spi->dev, "Unsupported master bus width %i\n", bpw);
  76                return -EINVAL;
  77        }
  78
  79        /* Setup SPI frequency divider */
  80        if (!speed || (speed >= hw->max_speed_hz))
  81                clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
  82                            SYSCON1_ADCKSEL(3), SYSCON1);
  83        else if (speed >= (hw->max_speed_hz / 2))
  84                clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
  85                            SYSCON1_ADCKSEL(2), SYSCON1);
  86        else if (speed >= (hw->max_speed_hz / 8))
  87                clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
  88                            SYSCON1_ADCKSEL(1), SYSCON1);
  89        else
  90                clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
  91                            SYSCON1_ADCKSEL(0), SYSCON1);
  92
  93        return 0;
  94}
  95
  96static int spi_clps711x_transfer_one_message(struct spi_master *master,
  97                                             struct spi_message *msg)
  98{
  99        struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 100        struct spi_transfer *xfer;
 101        int status = 0, cs = hw->chipselect[msg->spi->chip_select];
 102        u32 data;
 103
 104        spi_clps711x_setup_mode(msg->spi);
 105
 106        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 107                if (spi_clps711x_setup_xfer(msg->spi, xfer)) {
 108                        status = -EINVAL;
 109                        goto out_xfr;
 110                }
 111
 112                gpio_set_value(cs, !!(msg->spi->mode & SPI_CS_HIGH));
 113
 114                INIT_COMPLETION(hw->done);
 115
 116                hw->count = 0;
 117                hw->len = xfer->len;
 118                hw->tx_buf = (u8 *)xfer->tx_buf;
 119                hw->rx_buf = (u8 *)xfer->rx_buf;
 120
 121                /* Initiate transfer */
 122                data = hw->tx_buf ? hw->tx_buf[hw->count] : 0;
 123                clps_writel(data | SYNCIO_FRMLEN(8) | SYNCIO_TXFRMEN, SYNCIO);
 124
 125                wait_for_completion(&hw->done);
 126
 127                if (xfer->delay_usecs)
 128                        udelay(xfer->delay_usecs);
 129
 130                if (xfer->cs_change ||
 131                    list_is_last(&xfer->transfer_list, &msg->transfers))
 132                        gpio_set_value(cs, !(msg->spi->mode & SPI_CS_HIGH));
 133
 134                msg->actual_length += xfer->len;
 135        }
 136
 137out_xfr:
 138        msg->status = status;
 139        spi_finalize_current_message(master);
 140
 141        return 0;
 142}
 143
 144static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
 145{
 146        struct spi_clps711x_data *hw = (struct spi_clps711x_data *)dev_id;
 147        u32 data;
 148
 149        /* Handle RX */
 150        data = clps_readb(SYNCIO);
 151        if (hw->rx_buf)
 152                hw->rx_buf[hw->count] = (u8)data;
 153
 154        hw->count++;
 155
 156        /* Handle TX */
 157        if (hw->count < hw->len) {
 158                data = hw->tx_buf ? hw->tx_buf[hw->count] : 0;
 159                clps_writel(data | SYNCIO_FRMLEN(8) | SYNCIO_TXFRMEN, SYNCIO);
 160        } else
 161                complete(&hw->done);
 162
 163        return IRQ_HANDLED;
 164}
 165
 166static int spi_clps711x_probe(struct platform_device *pdev)
 167{
 168        int i, ret;
 169        struct spi_master *master;
 170        struct spi_clps711x_data *hw;
 171        struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
 172
 173        if (!pdata) {
 174                dev_err(&pdev->dev, "No platform data supplied\n");
 175                return -EINVAL;
 176        }
 177
 178        if (pdata->num_chipselect < 1) {
 179                dev_err(&pdev->dev, "At least one CS must be defined\n");
 180                return -EINVAL;
 181        }
 182
 183        master = spi_alloc_master(&pdev->dev,
 184                                  sizeof(struct spi_clps711x_data) +
 185                                  sizeof(int) * pdata->num_chipselect);
 186        if (!master) {
 187                dev_err(&pdev->dev, "SPI allocating memory error\n");
 188                return -ENOMEM;
 189        }
 190
 191        master->bus_num = pdev->id;
 192        master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
 193        master->num_chipselect = pdata->num_chipselect;
 194        master->setup = spi_clps711x_setup;
 195        master->transfer_one_message = spi_clps711x_transfer_one_message;
 196
 197        hw = spi_master_get_devdata(master);
 198
 199        for (i = 0; i < master->num_chipselect; i++) {
 200                hw->chipselect[i] = pdata->chipselect[i];
 201                if (!gpio_is_valid(hw->chipselect[i])) {
 202                        dev_err(&pdev->dev, "Invalid CS GPIO %i\n", i);
 203                        ret = -EINVAL;
 204                        goto err_out;
 205                }
 206                if (gpio_request(hw->chipselect[i], DRIVER_NAME)) {
 207                        dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
 208                        ret = -EINVAL;
 209                        goto err_out;
 210                }
 211        }
 212
 213        hw->spi_clk = devm_clk_get(&pdev->dev, "spi");
 214        if (IS_ERR(hw->spi_clk)) {
 215                dev_err(&pdev->dev, "Can't get clocks\n");
 216                ret = PTR_ERR(hw->spi_clk);
 217                goto err_out;
 218        }
 219        hw->max_speed_hz = clk_get_rate(hw->spi_clk);
 220
 221        init_completion(&hw->done);
 222        platform_set_drvdata(pdev, master);
 223
 224        /* Disable extended mode due hardware problems */
 225        clps_writew(clps_readw(SYSCON3) & ~SYSCON3_ADCCON, SYSCON3);
 226
 227        /* Clear possible pending interrupt */
 228        clps_readl(SYNCIO);
 229
 230        ret = devm_request_irq(&pdev->dev, IRQ_SSEOTI, spi_clps711x_isr, 0,
 231                               dev_name(&pdev->dev), hw);
 232        if (ret) {
 233                dev_err(&pdev->dev, "Can't request IRQ\n");
 234                clk_put(hw->spi_clk);
 235                goto clk_out;
 236        }
 237
 238        ret = spi_register_master(master);
 239        if (!ret) {
 240                dev_info(&pdev->dev,
 241                         "SPI bus driver initialized. Master clock %u Hz\n",
 242                         hw->max_speed_hz);
 243                return 0;
 244        }
 245
 246        dev_err(&pdev->dev, "Failed to register master\n");
 247        devm_free_irq(&pdev->dev, IRQ_SSEOTI, hw);
 248
 249clk_out:
 250        devm_clk_put(&pdev->dev, hw->spi_clk);
 251
 252err_out:
 253        while (--i >= 0)
 254                if (gpio_is_valid(hw->chipselect[i]))
 255                        gpio_free(hw->chipselect[i]);
 256
 257        platform_set_drvdata(pdev, NULL);
 258        spi_master_put(master);
 259        kfree(master);
 260
 261        return ret;
 262}
 263
 264static int spi_clps711x_remove(struct platform_device *pdev)
 265{
 266        int i;
 267        struct spi_master *master = platform_get_drvdata(pdev);
 268        struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 269
 270        devm_free_irq(&pdev->dev, IRQ_SSEOTI, hw);
 271
 272        for (i = 0; i < master->num_chipselect; i++)
 273                if (gpio_is_valid(hw->chipselect[i]))
 274                        gpio_free(hw->chipselect[i]);
 275
 276        devm_clk_put(&pdev->dev, hw->spi_clk);
 277        platform_set_drvdata(pdev, NULL);
 278        spi_unregister_master(master);
 279        kfree(master);
 280
 281        return 0;
 282}
 283
 284static struct platform_driver clps711x_spi_driver = {
 285        .driver = {
 286                .name   = DRIVER_NAME,
 287                .owner  = THIS_MODULE,
 288        },
 289        .probe  = spi_clps711x_probe,
 290        .remove = spi_clps711x_remove,
 291};
 292module_platform_driver(clps711x_spi_driver);
 293
 294MODULE_LICENSE("GPL");
 295MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 296MODULE_DESCRIPTION("CLPS711X SPI bus driver");
 297
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