drivers/w1/masters/mxc_w1.c

   1 /*
   2  * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
   3  * Copyright 2008 Luotao Fu, kernel@pengutronix.de
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version 2
   8  * of the License, or (at your option) any later version.
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  *
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/clk.h>
  24 #include <linux/delay.h>
  25 #include <linux/io.h>
  26
  27 #include "../w1.h"
  28 #include "../w1_int.h"
  29 #include "../w1_log.h"
  30
  31 /* According to the mx27 Datasheet the reset procedure should take up to about
  32  * 1350us. We set the timeout to 500*100us = 50ms for sure */
  33 #define MXC_W1_RESET_TIMEOUT 500
  34
  35 /*
  36  * MXC W1 Register offsets
  37  */
  38 #define MXC_W1_CONTROL          0x00
  39 #define MXC_W1_TIME_DIVIDER     0x02
  40 #define MXC_W1_RESET            0x04
  41 #define MXC_W1_COMMAND          0x06
  42 #define MXC_W1_TXRX             0x08
  43 #define MXC_W1_INTERRUPT        0x0A
  44 #define MXC_W1_INTERRUPT_EN     0x0C
  45
  46 struct mxc_w1_device {
  47         void __iomem *regs;
  48         unsigned int clkdiv;
  49         struct clk *clk;
  50         struct w1_bus_master bus_master;
  51 };
  52
  53 /*
  54  * this is the low level routine to
  55  * reset the device on the One Wire interface
  56  * on the hardware
  57  */
  58 static u8 mxc_w1_ds2_reset_bus(void *data)
  59 {
  60         u8 reg_val;
  61         unsigned int timeout_cnt = 0;
  62         struct mxc_w1_device *dev = data;
  63
  64         __raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL));
  65
  66         while (1) {
  67                 reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL);
  68
  69                 if (((reg_val >> 7) & 0x1) == 0 ||
  70                     timeout_cnt > MXC_W1_RESET_TIMEOUT)
  71                         break;
  72                 else
  73                         timeout_cnt++;
  74
  75                 udelay(100);
  76         }
  77         return (reg_val >> 7) & 0x1;
  78 }
  79
  80 /*
  81  * this is the low level routine to read/write a bit on the One Wire
  82  * interface on the hardware. It does write 0 if parameter bit is set
  83  * to 0, otherwise a write 1/read.
  84  */
  85 static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
  86 {
  87         struct mxc_w1_device *mdev = data;
  88         void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL;
  89         unsigned int timeout_cnt = 400; /* Takes max. 120us according to
  90                                          * datasheet.
  91                                          */
  92
  93         __raw_writeb((1 << (5 - bit)), ctrl_addr);
  94
  95         while (timeout_cnt--) {
  96                 if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1))
  97                         break;
  98
  99                 udelay(1);
 100         }
 101
 102         return ((__raw_readb(ctrl_addr)) >> 3) & 0x1;
 103 }
 104
 105 static int __init mxc_w1_probe(struct platform_device *pdev)
 106 {
 107         struct mxc_w1_device *mdev;
 108         struct resource *res;
 109         int err = 0;
 110
 111         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 112         if (!res)
 113                 return -ENODEV;
 114
 115         mdev = kzalloc(sizeof(struct mxc_w1_device), GFP_KERNEL);
 116         if (!mdev)
 117                 return -ENOMEM;
 118
 119         mdev->clk = clk_get(&pdev->dev, "owire_clk");
 120         if (!mdev->clk) {
 121                 err = -ENODEV;
 122                 goto failed_clk;
 123         }
 124
 125         mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;
 126
 127         res = request_mem_region(res->start, resource_size(res),
 128                                 "mxc_w1");
 129         if (!res) {
 130                 err = -EBUSY;
 131                 goto failed_req;
 132         }
 133
 134         mdev->regs = ioremap(res->start, resource_size(res));
 135         if (!mdev->regs) {
 136                 printk(KERN_ERR "Cannot map frame buffer registers\n");
 137                 goto failed_ioremap;
 138         }
 139
 140         clk_enable(mdev->clk);
 141         __raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
 142
 143         mdev->bus_master.data = mdev;
 144         mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;
 145         mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit;
 146
 147         err = w1_add_master_device(&mdev->bus_master);
 148
 149         if (err)
 150                 goto failed_add;
 151
 152         platform_set_drvdata(pdev, mdev);
 153         return 0;
 154
 155 failed_add:
 156         iounmap(mdev->regs);
 157 failed_ioremap:
 158         release_mem_region(res->start, resource_size(res));
 159 failed_req:
 160         clk_put(mdev->clk);
 161 failed_clk:
 162         kfree(mdev);
 163         return err;
 164 }
 165
 166 /*
 167  * disassociate the w1 device from the driver
 168  */
 169 static int mxc_w1_remove(struct platform_device *pdev)
 170 {
 171         struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
 172         struct resource *res;
 173
 174         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 175
 176         w1_remove_master_device(&mdev->bus_master);
 177
 178         iounmap(mdev->regs);
 179         release_mem_region(res->start, resource_size(res));
 180         clk_disable(mdev->clk);
 181         clk_put(mdev->clk);
 182
 183         platform_set_drvdata(pdev, NULL);
 184
 185         return 0;
 186 }
 187
 188 static struct platform_driver mxc_w1_driver = {
 189         .driver = {
 190                    .name = "mxc_w1",
 191         },
 192         .probe = mxc_w1_probe,
 193         .remove = mxc_w1_remove,
 194 };
 195
 196 static int __init mxc_w1_init(void)
 197 {
 198         return platform_driver_register(&mxc_w1_driver);
 199 }
 200
 201 static void mxc_w1_exit(void)
 202 {
 203         platform_driver_unregister(&mxc_w1_driver);
 204 }
 205
 206 module_init(mxc_w1_init);
 207 module_exit(mxc_w1_exit);
 208
 209 MODULE_LICENSE("GPL");
 210 MODULE_AUTHOR("Freescale Semiconductors Inc");
 211 MODULE_DESCRIPTION("Driver for One-Wire on MXC");