drivers/cbus/cbus.c

   1 /*
   2  * drivers/cbus/cbus.c
   3  *
   4  * Support functions for CBUS serial protocol
   5  *
   6  * Copyright (C) 2004, 2005 Nokia Corporation
   7  *
   8  * Written by Juha Yrjölä <juha.yrjola@nokia.com>,
   9  *            David Weinehall <david.weinehall@nokia.com>, and
  10  *            Mikko Ylinen <mikko.k.ylinen@nokia.com>
  11  *
  12  * This file is subject to the terms and conditions of the GNU General
  13  * Public License. See the file "COPYING" in the main directory of this
  14  * archive for more details.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24  */
  25
  26 #include <linux/device.h>
  27 #include <linux/init.h>
  28 #include <linux/kernel.h>
  29 #include <linux/delay.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/gpio.h>
  32
  33 #include <asm/io.h>
  34 #include <asm/mach-types.h>
  35
  36 #include <plat/board.h>
  37
  38 #include "cbus.h"
  39
  40 struct cbus_host *cbus_host = NULL;
  41
  42 #ifdef CONFIG_ARCH_OMAP1
  43 /* We use our own MPUIO functions to get closer to 1MHz bus speed */
  44
  45 static inline void cbus_set_gpio_direction(u32 base, int mpuio, int is_input)
  46 {
  47         u16 w;
  48
  49         mpuio &= 0x0f;
  50         w = __raw_readw(base + OMAP_MPUIO_IO_CNTL);
  51         if (is_input)
  52                 w |= 1 << mpuio;
  53         else
  54                 w &= ~(1 << mpuio);
  55         __raw_writew(w, base + OMAP_MPUIO_IO_CNTL);
  56
  57 }
  58
  59 static inline void cbus_set_gpio_dataout(u32 base, int mpuio, int enable)
  60 {
  61         u16 w;
  62
  63         mpuio &= 0x0f;
  64         w = __raw_readw(base + OMAP_MPUIO_OUTPUT);
  65         if (enable)
  66                 w |= 1 << mpuio;
  67         else
  68                 w &= ~(1 << mpuio);
  69         __raw_writew(w, base + OMAP_MPUIO_OUTPUT);
  70 }
  71
  72 static inline int cbus_get_gpio_datain(u32 base, int mpuio)
  73 {
  74         mpuio &= 0x0f;
  75
  76         return (__raw_readw(base + OMAP_MPUIO_INPUT_LATCH) & (1 << mpuio)) != 0;
  77 }
  78
  79 static void cbus_send_bit(struct cbus_host *host, u32 base, int bit,
  80                           int set_to_input)
  81 {
  82         cbus_set_gpio_dataout(base, host->dat_gpio, bit ? 1 : 0);
  83         cbus_set_gpio_dataout(base, host->clk_gpio, 1);
  84
  85         /* The data bit is read on the rising edge of CLK */
  86         if (set_to_input)
  87                 cbus_set_gpio_direction(base, host->dat_gpio, 1);
  88
  89         cbus_set_gpio_dataout(base, host->clk_gpio, 0);
  90 }
  91
  92 static u8 cbus_receive_bit(struct cbus_host *host, u32 base)
  93 {
  94         u8 ret;
  95
  96         cbus_set_gpio_dataout(base, host->clk_gpio, 1);
  97         ret = cbus_get_gpio_datain(base, host->dat_gpio);
  98         cbus_set_gpio_dataout(base, host->clk_gpio, 0);
  99
 100         return ret;
 101 }
 102
 103 #define cbus_output(base, gpio, val)    cbus_set_gpio_direction(base, gpio, 0)
 104
 105 #else
 106
 107 #define cbus_output(base, gpio, val)    gpio_direction_output(gpio, val)
 108 #define cbus_set_gpio_dataout(base, gpio, enable) gpio_set_value(gpio, enable)
 109 #define cbus_get_gpio_datain(base, int, gpio) gpio_get_value(gpio)
 110
 111 static void _cbus_send_bit(struct cbus_host *host, int bit, int set_to_input)
 112 {
 113         gpio_set_value(host->dat_gpio, bit ? 1 : 0);
 114         gpio_set_value(host->clk_gpio, 1);
 115
 116         /* The data bit is read on the rising edge of CLK */
 117         if (set_to_input)
 118                 gpio_direction_input(host->dat_gpio);
 119
 120         gpio_set_value(host->clk_gpio, 0);
 121 }
 122
 123 static u8 _cbus_receive_bit(struct cbus_host *host)
 124 {
 125         u8 ret;
 126
 127         gpio_set_value(host->clk_gpio, 1);
 128         ret = gpio_get_value(host->dat_gpio);
 129         gpio_set_value(host->clk_gpio, 0);
 130
 131         return ret;
 132 }
 133
 134 #define cbus_send_bit(host, base, bit, set_to_input) _cbus_send_bit(host, bit, set_to_input)
 135 #define cbus_receive_bit(host, base) _cbus_receive_bit(host)
 136
 137 #endif
 138
 139 static int cbus_transfer(struct cbus_host *host, int dev, int reg, int data)
 140 {
 141         int i;
 142         int is_read = 0;
 143         unsigned long flags;
 144         u32 base;
 145
 146 #ifdef CONFIG_ARCH_OMAP1
 147         base = OMAP1_IO_ADDRESS(OMAP1_MPUIO_BASE);
 148 #else
 149         base = 0;
 150 #endif
 151
 152         if (data < 0)
 153                 is_read = 1;
 154
 155         /* We don't want interrupts disturbing our transfer */
 156         spin_lock_irqsave(&host->lock, flags);
 157
 158         /* Reset state and start of transfer, SEL stays down during transfer */
 159         cbus_set_gpio_dataout(base, host->sel_gpio, 0);
 160
 161         /* Set the DAT pin to output */
 162         cbus_output(base, host->dat_gpio, 1);
 163
 164         /* Send the device address */
 165         for (i = 3; i > 0; i--)
 166                 cbus_send_bit(host, base, dev & (1 << (i - 1)), 0);
 167
 168         /* Send the rw flag */
 169         cbus_send_bit(host, base, is_read, 0);
 170
 171         /* Send the register address */
 172         for (i = 5; i > 0; i--) {
 173                 int set_to_input = 0;
 174
 175                 if (is_read && i == 1)
 176                         set_to_input = 1;
 177
 178                 cbus_send_bit(host, base, reg & (1 << (i - 1)), set_to_input);
 179         }
 180
 181         if (!is_read) {
 182                 for (i = 16; i > 0; i--)
 183                         cbus_send_bit(host, base, data & (1 << (i - 1)), 0);
 184         } else {
 185                 cbus_set_gpio_dataout(base, host->clk_gpio, 1);
 186                 data = 0;
 187
 188                 for (i = 16; i > 0; i--) {
 189                         u8 bit = cbus_receive_bit(host, base);
 190
 191                         if (bit)
 192                                 data |= 1 << (i - 1);
 193                 }
 194         }
 195
 196         /* Indicate end of transfer, SEL goes up until next transfer */
 197         cbus_set_gpio_dataout(base, host->sel_gpio, 1);
 198         cbus_set_gpio_dataout(base, host->clk_gpio, 1);
 199         cbus_set_gpio_dataout(base, host->clk_gpio, 0);
 200
 201         spin_unlock_irqrestore(&host->lock, flags);
 202
 203         return is_read ? data : 0;
 204 }
 205
 206 /*
 207  * Read a given register from the device
 208  */
 209 int cbus_read_reg(struct cbus_host *host, int dev, int reg)
 210 {
 211         return cbus_host ? cbus_transfer(host, dev, reg, -1) : -ENODEV;
 212 }
 213
 214 /*
 215  * Write to a given register of the device
 216  */
 217 int cbus_write_reg(struct cbus_host *host, int dev, int reg, u16 val)
 218 {
 219         return cbus_host ? cbus_transfer(host, dev, reg, (int)val) : -ENODEV;
 220 }
 221
 222 int __init cbus_bus_init(void)
 223 {
 224         struct cbus_host *chost;
 225         int ret;
 226
 227         chost = kmalloc(sizeof (*chost), GFP_KERNEL);
 228         if (chost == NULL)
 229                 return -ENOMEM;
 230
 231         memset(chost, 0, sizeof (*chost));
 232
 233         spin_lock_init(&chost->lock);
 234
 235         /* REVISIT: Pass these from board-*.c files in platform_data */
 236         if (machine_is_nokia770()) {
 237                 chost->clk_gpio = OMAP_MPUIO(11);
 238                 chost->dat_gpio = OMAP_MPUIO(10);
 239                 chost->sel_gpio = OMAP_MPUIO(9);
 240         } else if (machine_is_nokia_n800() || machine_is_nokia_n810() ||
 241                         machine_is_nokia_n810_wimax()) {
 242                 chost->clk_gpio = 66;
 243                 chost->dat_gpio = 65;
 244                 chost->sel_gpio = 64;
 245         } else {
 246                 printk(KERN_ERR "cbus: Unsupported board\n");
 247                 ret = -ENODEV;
 248                 goto exit1;
 249         }
 250
 251 #ifdef CONFIG_ARCH_OMAP1
 252         if (!OMAP_GPIO_IS_MPUIO(chost->clk_gpio) ||
 253             !OMAP_GPIO_IS_MPUIO(chost->dat_gpio) ||
 254             !OMAP_GPIO_IS_MPUIO(chost->sel_gpio)) {
 255                 printk(KERN_ERR "cbus: Only MPUIO pins supported\n");
 256                 ret = -ENODEV;
 257                 goto exit1;
 258         }
 259 #endif
 260
 261         if ((ret = gpio_request(chost->clk_gpio, "CBUS clk")) < 0)
 262                 goto exit1;
 263
 264         if ((ret = gpio_request(chost->dat_gpio, "CBUS data")) < 0)
 265                 goto exit2;
 266
 267         if ((ret = gpio_request(chost->sel_gpio, "CBUS sel")) < 0)
 268                 goto exit3;
 269
 270         gpio_direction_output(chost->clk_gpio, 0);
 271         gpio_direction_input(chost->dat_gpio);
 272         gpio_direction_output(chost->sel_gpio, 1);
 273
 274         gpio_set_value(chost->clk_gpio, 1);
 275         gpio_set_value(chost->clk_gpio, 0);
 276
 277         cbus_host = chost;
 278
 279         return 0;
 280 exit3:
 281         gpio_free(chost->dat_gpio);
 282 exit2:
 283         gpio_free(chost->clk_gpio);
 284 exit1:
 285         kfree(chost);
 286         return ret;
 287 }
 288
 289 subsys_initcall(cbus_bus_init);
 290
 291 EXPORT_SYMBOL(cbus_host);
 292 EXPORT_SYMBOL(cbus_read_reg);
 293 EXPORT_SYMBOL(cbus_write_reg);
 294
 295 MODULE_DESCRIPTION("CBUS serial protocol");
 296 MODULE_LICENSE("GPL");
 297 MODULE_AUTHOR("Juha Yrjölä, David Weinehall, and Mikko Ylinen");