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