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
  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 && 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->dev.platform_data;
 133
 134         /* setup spi bitbang adaptor */
 135         sp->bitbang.master = spi_master_get(master);
 136         sp->bitbang.master->bus_num = sp->info->bus_num;
 137         sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
 138         sp->bitbang.chipselect = sh_sci_spi_chipselect;
 139
 140         sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
 141         sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
 142         sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
 143         sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
 144
 145         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 146         if (r == NULL) {
 147                 ret = -ENOENT;
 148                 goto err1;
 149         }
 150         sp->membase = ioremap(r->start, resource_size(r));
 151         if (!sp->membase) {
 152                 ret = -ENXIO;
 153                 goto err1;
 154         }
 155         sp->val = ioread8(SCSPTR(sp));
 156         setbits(sp, PIN_INIT, 1);
 157
 158         ret = spi_bitbang_start(&sp->bitbang);
 159         if (!ret)
 160                 return 0;
 161
 162         setbits(sp, PIN_INIT, 0);
 163         iounmap(sp->membase);
 164  err1:
 165         spi_master_put(sp->bitbang.master);
 166  err0:
 167         return ret;
 168 }
 169
 170 static int sh_sci_spi_remove(struct platform_device *dev)
 171 {
 172         struct sh_sci_spi *sp = platform_get_drvdata(dev);
 173
 174         iounmap(sp->membase);
 175         setbits(sp, PIN_INIT, 0);
 176         spi_bitbang_stop(&sp->bitbang);
 177         spi_master_put(sp->bitbang.master);
 178         return 0;
 179 }
 180
 181 static struct platform_driver sh_sci_spi_drv = {
 182         .probe          = sh_sci_spi_probe,
 183         .remove         = sh_sci_spi_remove,
 184         .driver         = {
 185                 .name   = "spi_sh_sci",
 186                 .owner  = THIS_MODULE,
 187         },
 188 };
 189
 190 static int __init sh_sci_spi_init(void)
 191 {
 192         return platform_driver_register(&sh_sci_spi_drv);
 193 }
 194 module_init(sh_sci_spi_init);
 195
 196 static void __exit sh_sci_spi_exit(void)
 197 {
 198         platform_driver_unregister(&sh_sci_spi_drv);
 199 }
 200 module_exit(sh_sci_spi_exit);
 201
 202 MODULE_DESCRIPTION("SH SCI SPI Driver");
 203 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 204 MODULE_LICENSE("GPL");
 205 MODULE_ALIAS("platform:spi_sh_sci");