drivers/spi/spi-sh-sci.c

   1 /*
   2  * SH SCI SPI interface
   3  *
   4  * Copyright (c) 2008 Magnus Damm
   5  *
   6  * Based on S3C24XX GPIO based SPI driver, which is:
   7  *   Copyright (c) 2006 Ben Dooks
   8  *   Copyright (c) 2006 Simtec Electronics
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/delay.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/workqueue.h>
  20 #include <linux/platform_device.h>
  21
  22 #include <linux/spi/spi.h>
  23 #include <linux/spi/spi_bitbang.h>
  24 #include <linux/module.h>
  25
  26 #include <asm/spi.h>
  27 #include <asm/io.h>
  28
  29 struct sh_sci_spi {
  30         struct spi_bitbang bitbang;
  31
  32         void __iomem *membase;
  33         unsigned char val;
  34         struct sh_spi_info *info;
  35         struct platform_device *dev;
  36 };
  37
  38 #define SCSPTR(sp)      (sp->membase + 0x1c)
  39 #define PIN_SCK         (1 << 2)
  40 #define PIN_TXD         (1 << 0)
  41 #define PIN_RXD         PIN_TXD
  42 #define PIN_INIT        ((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)
  43
  44 static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
  45 {
  46         /*
  47          * We are the only user of SCSPTR so no locking is required.
  48          * Reading bit 2 and 0 in SCSPTR gives pin state as input.
  49          * Writing the same bits sets the output value.
  50          * This makes regular read-modify-write difficult so we
  51          * use sp->val to keep track of the latest register value.
  52          */
  53
  54         if (on)
  55                 sp->val |= bits;
  56         else
  57                 sp->val &= ~bits;
  58
  59         iowrite8(sp->val, SCSPTR(sp));
  60 }
  61
  62 static inline void setsck(struct spi_device *dev, int on)
  63 {
  64         setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
  65 }
  66
  67 static inline void setmosi(struct spi_device *dev, int on)
  68 {
  69         setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
  70 }
  71
  72 static inline u32 getmiso(struct spi_device *dev)
  73 {
  74         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
  75
  76         return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
  77 }
  78
  79 #define spidelay(x) ndelay(x)
  80
  81 #include "spi-bitbang-txrx.h"
  82
  83 static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
  84                                       unsigned nsecs, u32 word, u8 bits)
  85 {
  86         return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
  87 }
  88
  89 static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
  90                                       unsigned nsecs, u32 word, u8 bits)
  91 {
  92         return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
  93 }
  94
  95 static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
  96                                       unsigned nsecs, u32 word, u8 bits)
  97 {
  98         return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
  99 }
 100
 101 static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
 102                                       unsigned nsecs, u32 word, u8 bits)
 103 {
 104         return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
 105 }
 106
 107 static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
 108 {
 109         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
 110
 111         if (sp->info->chip_select)
 112                 (sp->info->chip_select)(sp->info, dev->chip_select, value);
 113 }
 114
 115 static int sh_sci_spi_probe(struct platform_device *dev)
 116 {
 117         struct resource *r;
 118         struct spi_master *master;
 119         struct sh_sci_spi *sp;
 120         int ret;
 121
 122         master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
 123         if (master == NULL) {
 124                 dev_err(&dev->dev, "failed to allocate spi master\n");
 125                 ret = -ENOMEM;
 126                 goto err0;
 127         }
 128
 129         sp = spi_master_get_devdata(master);
 130
 131         platform_set_drvdata(dev, sp);
 132         sp->info = dev_get_platdata(&dev->dev);
 133         if (!sp->info) {
 134                 dev_err(&dev->dev, "platform data is missing\n");
 135                 ret = -ENOENT;
 136                 goto err1;
 137         }
 138
 139         /* setup spi bitbang adaptor */
 140         sp->bitbang.master = master;
 141         sp->bitbang.master->bus_num = sp->info->bus_num;
 142         sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
 143         sp->bitbang.chipselect = sh_sci_spi_chipselect;
 144
 145         sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
 146         sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
 147         sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
 148         sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
 149
 150         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 151         if (r == NULL) {
 152                 ret = -ENOENT;
 153                 goto err1;
 154         }
 155         sp->membase = ioremap(r->start, resource_size(r));
 156         if (!sp->membase) {
 157                 ret = -ENXIO;
 158                 goto err1;
 159         }
 160         sp->val = ioread8(SCSPTR(sp));
 161         setbits(sp, PIN_INIT, 1);
 162
 163         ret = spi_bitbang_start(&sp->bitbang);
 164         if (!ret)
 165                 return 0;
 166
 167         setbits(sp, PIN_INIT, 0);
 168         iounmap(sp->membase);
 169  err1:
 170         spi_master_put(sp->bitbang.master);
 171  err0:
 172         return ret;
 173 }
 174
 175 static int sh_sci_spi_remove(struct platform_device *dev)
 176 {
 177         struct sh_sci_spi *sp = platform_get_drvdata(dev);
 178
 179         iounmap(sp->membase);
 180         setbits(sp, PIN_INIT, 0);
 181         spi_bitbang_stop(&sp->bitbang);
 182         spi_master_put(sp->bitbang.master);
 183         return 0;
 184 }
 185
 186 static struct platform_driver sh_sci_spi_drv = {
 187         .probe          = sh_sci_spi_probe,
 188         .remove         = sh_sci_spi_remove,
 189         .driver         = {
 190                 .name   = "spi_sh_sci",
 191                 .owner  = THIS_MODULE,
 192         },
 193 };
 194 module_platform_driver(sh_sci_spi_drv);
 195
 196 MODULE_DESCRIPTION("SH SCI SPI Driver");
 197 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 198 MODULE_LICENSE("GPL");
 199 MODULE_ALIAS("platform:spi_sh_sci");