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/init.h>
  18 #include <linux/delay.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/workqueue.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <linux/spi/spi.h>
  24 #include <linux/spi/spi_bitbang.h>
  25 #include <linux/module.h>
  26
  27 #include <asm/spi.h>
  28 #include <asm/io.h>
  29
  30 struct sh_sci_spi {
  31         struct spi_bitbang bitbang;
  32
  33         void __iomem *membase;
  34         unsigned char val;
  35         struct sh_spi_info *info;
  36         struct platform_device *dev;
  37 };
  38
  39 #define SCSPTR(sp)      (sp->membase + 0x1c)
  40 #define PIN_SCK         (1 << 2)
  41 #define PIN_TXD         (1 << 0)
  42 #define PIN_RXD         PIN_TXD
  43 #define PIN_INIT        ((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)
  44
  45 static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
  46 {
  47         /*
  48          * We are the only user of SCSPTR so no locking is required.
  49          * Reading bit 2 and 0 in SCSPTR gives pin state as input.
  50          * Writing the same bits sets the output value.
  51          * This makes regular read-modify-write difficult so we
  52          * use sp->val to keep track of the latest register value.
  53          */
  54
  55         if (on)
  56                 sp->val |= bits;
  57         else
  58                 sp->val &= ~bits;
  59
  60         iowrite8(sp->val, SCSPTR(sp));
  61 }
  62
  63 static inline void setsck(struct spi_device *dev, int on)
  64 {
  65         setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
  66 }
  67
  68 static inline void setmosi(struct spi_device *dev, int on)
  69 {
  70         setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
  71 }
  72
  73 static inline u32 getmiso(struct spi_device *dev)
  74 {
  75         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
  76
  77         return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
  78 }
  79
  80 #define spidelay(x) ndelay(x)
  81
  82 #include "spi-bitbang-txrx.h"
  83
  84 static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
  85                                       unsigned nsecs, u32 word, u8 bits)
  86 {
  87         return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
  88 }
  89
  90 static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
  91                                       unsigned nsecs, u32 word, u8 bits)
  92 {
  93         return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
  94 }
  95
  96 static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
  97                                       unsigned nsecs, u32 word, u8 bits)
  98 {
  99         return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
 100 }
 101
 102 static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
 103                                       unsigned nsecs, u32 word, u8 bits)
 104 {
 105         return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
 106 }
 107
 108 static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
 109 {
 110         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
 111
 112         if (sp->info && sp->info->chip_select)
 113                 (sp->info->chip_select)(sp->info, dev->chip_select, value);
 114 }
 115
 116 static int sh_sci_spi_probe(struct platform_device *dev)
 117 {
 118         struct resource *r;
 119         struct spi_master *master;
 120         struct sh_sci_spi *sp;
 121         int ret;
 122
 123         master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
 124         if (master == NULL) {
 125                 dev_err(&dev->dev, "failed to allocate spi master\n");
 126                 ret = -ENOMEM;
 127                 goto err0;
 128         }
 129
 130         sp = spi_master_get_devdata(master);
 131
 132         platform_set_drvdata(dev, sp);
 133         sp->info = dev->dev.platform_data;
 134
 135         /* setup spi bitbang adaptor */
 136         sp->bitbang.master = spi_master_get(master);
 137         sp->bitbang.master->bus_num = sp->info->bus_num;
 138         sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
 139         sp->bitbang.chipselect = sh_sci_spi_chipselect;
 140
 141         sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
 142         sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
 143         sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
 144         sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
 145
 146         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 147         if (r == NULL) {
 148                 ret = -ENOENT;
 149                 goto err1;
 150         }
 151         sp->membase = ioremap(r->start, resource_size(r));
 152         if (!sp->membase) {
 153                 ret = -ENXIO;
 154                 goto err1;
 155         }
 156         sp->val = ioread8(SCSPTR(sp));
 157         setbits(sp, PIN_INIT, 1);
 158
 159         ret = spi_bitbang_start(&sp->bitbang);
 160         if (!ret)
 161                 return 0;
 162
 163         setbits(sp, PIN_INIT, 0);
 164         iounmap(sp->membase);
 165  err1:
 166         spi_master_put(sp->bitbang.master);
 167  err0:
 168         return ret;
 169 }
 170
 171 static int sh_sci_spi_remove(struct platform_device *dev)
 172 {
 173         struct sh_sci_spi *sp = platform_get_drvdata(dev);
 174
 175         iounmap(sp->membase);
 176         setbits(sp, PIN_INIT, 0);
 177         spi_bitbang_stop(&sp->bitbang);
 178         spi_master_put(sp->bitbang.master);
 179         return 0;
 180 }
 181
 182 static struct platform_driver sh_sci_spi_drv = {
 183         .probe          = sh_sci_spi_probe,
 184         .remove         = sh_sci_spi_remove,
 185         .driver         = {
 186                 .name   = "spi_sh_sci",
 187                 .owner  = THIS_MODULE,
 188         },
 189 };
 190
 191 static int __init sh_sci_spi_init(void)
 192 {
 193         return platform_driver_register(&sh_sci_spi_drv);
 194 }
 195 module_init(sh_sci_spi_init);
 196
 197 static void __exit sh_sci_spi_exit(void)
 198 {
 199         platform_driver_unregister(&sh_sci_spi_drv);
 200 }
 201 module_exit(sh_sci_spi_exit);
 202
 203 MODULE_DESCRIPTION("SH SCI SPI Driver");
 204 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 205 MODULE_LICENSE("GPL");
 206 MODULE_ALIAS("platform:spi_sh_sci");