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"); 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"); 212