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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/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 {
 85         return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 86 }
 87 
 88 static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
 89                                       unsigned nsecs, u32 word, u8 bits)
 90 {
 91         return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
 92 }
 93 
 94 static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
 95                                       unsigned nsecs, u32 word, u8 bits)
 96 {
 97         return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
 98 }
 99 
100 static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
101                                       unsigned nsecs, u32 word, u8 bits)
102 {
103         return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, 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                 .owner  = THIS_MODULE,
191         },
192 };
193 module_platform_driver(sh_sci_spi_drv);
194 
195 MODULE_DESCRIPTION("SH SCI SPI Driver");
196 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
197 MODULE_LICENSE("GPL");
198 MODULE_ALIAS("platform:spi_sh_sci");
199 

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