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Linux/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_get_platdata(&dev->dev);
134 
135         /* setup spi bitbang adaptor */
136         sp->bitbang.master = 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 module_platform_driver(sh_sci_spi_drv);
191 
192 MODULE_DESCRIPTION("SH SCI SPI Driver");
193 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
194 MODULE_LICENSE("GPL");
195 MODULE_ALIAS("platform:spi_sh_sci");
196 

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