drivers/spi/spi-sh-sci.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * SH SCI SPI interface
   4  *
   5  * Copyright (c) 2008 Magnus Damm
   6  *
   7  * Based on S3C24XX GPIO based SPI driver, which is:
   8  *   Copyright (c) 2006 Ben Dooks
   9  *   Copyright (c) 2006 Simtec Electronics
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/delay.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/platform_device.h>
  16
  17 #include <linux/spi/spi.h>
  18 #include <linux/spi/spi_bitbang.h>
  19 #include <linux/module.h>
  20
  21 #include <asm/spi.h>
  22 #include <asm/io.h>
  23
  24 struct sh_sci_spi {
  25         struct spi_bitbang bitbang;
  26
  27         void __iomem *membase;
  28         unsigned char val;
  29         struct sh_spi_info *info;
  30         struct platform_device *dev;
  31 };
  32
  33 #define SCSPTR(sp)      (sp->membase + 0x1c)
  34 #define PIN_SCK         (1 << 2)
  35 #define PIN_TXD         (1 << 0)
  36 #define PIN_RXD         PIN_TXD
  37 #define PIN_INIT        ((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)
  38
  39 static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
  40 {
  41         /*
  42          * We are the only user of SCSPTR so no locking is required.
  43          * Reading bit 2 and 0 in SCSPTR gives pin state as input.
  44          * Writing the same bits sets the output value.
  45          * This makes regular read-modify-write difficult so we
  46          * use sp->val to keep track of the latest register value.
  47          */
  48
  49         if (on)
  50                 sp->val |= bits;
  51         else
  52                 sp->val &= ~bits;
  53
  54         iowrite8(sp->val, SCSPTR(sp));
  55 }
  56
  57 static inline void setsck(struct spi_device *dev, int on)
  58 {
  59         setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
  60 }
  61
  62 static inline void setmosi(struct spi_device *dev, int on)
  63 {
  64         setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
  65 }
  66
  67 static inline u32 getmiso(struct spi_device *dev)
  68 {
  69         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
  70
  71         return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
  72 }
  73
  74 #define spidelay(x) ndelay(x)
  75
  76 #include "spi-bitbang-txrx.h"
  77
  78 static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
  79                                  unsigned nsecs, u32 word, u8 bits,
  80                                  unsigned flags)
  81 {
  82         return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
  83 }
  84
  85 static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
  86                                  unsigned nsecs, u32 word, u8 bits,
  87                                  unsigned flags)
  88 {
  89         return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
  90 }
  91
  92 static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
  93                                  unsigned nsecs, u32 word, u8 bits,
  94                                  unsigned flags)
  95 {
  96         return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
  97 }
  98
  99 static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
 100                                  unsigned nsecs, u32 word, u8 bits,
 101                                  unsigned flags)
 102 {
 103         return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
 104 }
 105
 106 static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
 107 {
 108         struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
 109
 110         if (sp->info->chip_select)
 111                 (sp->info->chip_select)(sp->info, dev->chip_select, value);
 112 }
 113
 114 static int sh_sci_spi_probe(struct platform_device *dev)
 115 {
 116         struct resource *r;
 117         struct spi_master *master;
 118         struct sh_sci_spi *sp;
 119         int ret;
 120
 121         master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
 122         if (master == NULL) {
 123                 dev_err(&dev->dev, "failed to allocate spi master\n");
 124                 ret = -ENOMEM;
 125                 goto err0;
 126         }
 127
 128         sp = spi_master_get_devdata(master);
 129
 130         platform_set_drvdata(dev, sp);
 131         sp->info = dev_get_platdata(&dev->dev);
 132         if (!sp->info) {
 133                 dev_err(&dev->dev, "platform data is missing\n");
 134                 ret = -ENOENT;
 135                 goto err1;
 136         }
 137
 138         /* setup spi bitbang adaptor */
 139         sp->bitbang.master = master;
 140         sp->bitbang.master->bus_num = sp->info->bus_num;
 141         sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
 142         sp->bitbang.chipselect = sh_sci_spi_chipselect;
 143
 144         sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
 145         sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
 146         sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
 147         sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
 148
 149         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 150         if (r == NULL) {
 151                 ret = -ENOENT;
 152                 goto err1;
 153         }
 154         sp->membase = ioremap(r->start, resource_size(r));
 155         if (!sp->membase) {
 156                 ret = -ENXIO;
 157                 goto err1;
 158         }
 159         sp->val = ioread8(SCSPTR(sp));
 160         setbits(sp, PIN_INIT, 1);
 161
 162         ret = spi_bitbang_start(&sp->bitbang);
 163         if (!ret)
 164                 return 0;
 165
 166         setbits(sp, PIN_INIT, 0);
 167         iounmap(sp->membase);
 168  err1:
 169         spi_master_put(sp->bitbang.master);
 170  err0:
 171         return ret;
 172 }
 173
 174 static int sh_sci_spi_remove(struct platform_device *dev)
 175 {
 176         struct sh_sci_spi *sp = platform_get_drvdata(dev);
 177
 178         spi_bitbang_stop(&sp->bitbang);
 179         setbits(sp, PIN_INIT, 0);
 180         iounmap(sp->membase);
 181         spi_master_put(sp->bitbang.master);
 182         return 0;
 183 }
 184
 185 static struct platform_driver sh_sci_spi_drv = {
 186         .probe          = sh_sci_spi_probe,
 187         .remove         = sh_sci_spi_remove,
 188         .driver         = {
 189                 .name   = "spi_sh_sci",
 190         },
 191 };
 192 module_platform_driver(sh_sci_spi_drv);
 193
 194 MODULE_DESCRIPTION("SH SCI SPI Driver");
 195 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 196 MODULE_LICENSE("GPL");
 197 MODULE_ALIAS("platform:spi_sh_sci");