OpenWrt – Blame information for rev 4
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Rev | Author | Line No. | Line |
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1 | office | 1 | From 818357c73f5869dfc9e98224f91e116fd23d5246 Mon Sep 17 00:00:00 2001 |
2 | From: Luke Wren <luke@raspberrypi.org> |
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3 | Date: Fri, 21 Aug 2015 23:14:48 +0100 |
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4 | Subject: [PATCH 044/454] Add /dev/gpiomem device for rootless user GPIO access |
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5 | |||
6 | Signed-off-by: Luke Wren <luke@raspberrypi.org> |
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7 | |||
8 | bcm2835-gpiomem: Fix for ARCH_BCM2835 builds |
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9 | |||
10 | Build on ARCH_BCM2835, and fail to probe if no IO resource. |
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11 | |||
12 | See: https://github.com/raspberrypi/linux/issues/1154 |
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13 | --- |
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14 | drivers/char/broadcom/Kconfig | 9 + |
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15 | drivers/char/broadcom/Makefile | 3 + |
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16 | drivers/char/broadcom/bcm2835-gpiomem.c | 258 ++++++++++++++++++++++++ |
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17 | 3 files changed, 270 insertions(+) |
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18 | create mode 100644 drivers/char/broadcom/bcm2835-gpiomem.c |
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19 | |||
20 | --- a/drivers/char/broadcom/Kconfig |
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21 | +++ b/drivers/char/broadcom/Kconfig |
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22 | @@ -26,3 +26,12 @@ config BCM_VC_SM |
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23 | help |
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24 | Support for the VC shared memory on the Broadcom reference |
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25 | design. Uses the VCHIQ stack. |
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26 | + |
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27 | +config BCM2835_DEVGPIOMEM |
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28 | + tristate "/dev/gpiomem rootless GPIO access via mmap() on the BCM2835" |
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29 | + default m |
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30 | + help |
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31 | + Provides users with root-free access to the GPIO registers |
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32 | + on the 2835. Calling mmap(/dev/gpiomem) will map the GPIO |
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33 | + register page to the user's pointer. |
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34 | + |
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35 | --- a/drivers/char/broadcom/Makefile |
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36 | +++ b/drivers/char/broadcom/Makefile |
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37 | @@ -1,2 +1,5 @@ |
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38 | obj-$(CONFIG_BCM2708_VCMEM) += vc_mem.o |
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39 | obj-$(CONFIG_BCM_VC_SM) += vc_sm/ |
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40 | + |
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41 | +obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o |
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42 | + |
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43 | --- /dev/null |
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44 | +++ b/drivers/char/broadcom/bcm2835-gpiomem.c |
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45 | @@ -0,0 +1,258 @@ |
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46 | +/** |
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47 | + * GPIO memory device driver |
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48 | + * |
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49 | + * Creates a chardev /dev/gpiomem which will provide user access to |
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50 | + * the BCM2835's GPIO registers when it is mmap()'d. |
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51 | + * No longer need root for user GPIO access, but without relaxing permissions |
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52 | + * on /dev/mem. |
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53 | + * |
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54 | + * Written by Luke Wren <luke@raspberrypi.org> |
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55 | + * Copyright (c) 2015, Raspberry Pi (Trading) Ltd. |
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56 | + * |
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57 | + * Redistribution and use in source and binary forms, with or without |
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58 | + * modification, are permitted provided that the following conditions |
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59 | + * are met: |
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60 | + * 1. Redistributions of source code must retain the above copyright |
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61 | + * notice, this list of conditions, and the following disclaimer, |
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62 | + * without modification. |
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63 | + * 2. Redistributions in binary form must reproduce the above copyright |
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64 | + * notice, this list of conditions and the following disclaimer in the |
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65 | + * documentation and/or other materials provided with the distribution. |
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66 | + * 3. The names of the above-listed copyright holders may not be used |
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67 | + * to endorse or promote products derived from this software without |
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68 | + * specific prior written permission. |
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69 | + * |
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70 | + * ALTERNATIVELY, this software may be distributed under the terms of the |
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71 | + * GNU General Public License ("GPL") version 2, as published by the Free |
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72 | + * Software Foundation. |
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73 | + * |
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74 | + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
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75 | + * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
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76 | + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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77 | + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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78 | + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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79 | + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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80 | + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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81 | + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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82 | + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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83 | + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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84 | + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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85 | + */ |
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86 | + |
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87 | +#include <linux/kernel.h> |
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88 | +#include <linux/module.h> |
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89 | +#include <linux/of.h> |
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90 | +#include <linux/platform_device.h> |
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91 | +#include <linux/mm.h> |
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92 | +#include <linux/slab.h> |
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93 | +#include <linux/cdev.h> |
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94 | +#include <linux/pagemap.h> |
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95 | +#include <linux/io.h> |
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96 | + |
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97 | +#define DEVICE_NAME "bcm2835-gpiomem" |
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98 | +#define DRIVER_NAME "gpiomem-bcm2835" |
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99 | +#define DEVICE_MINOR 0 |
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100 | + |
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101 | +struct bcm2835_gpiomem_instance { |
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102 | + unsigned long gpio_regs_phys; |
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103 | + struct device *dev; |
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104 | +}; |
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105 | + |
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106 | +static struct cdev bcm2835_gpiomem_cdev; |
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107 | +static dev_t bcm2835_gpiomem_devid; |
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108 | +static struct class *bcm2835_gpiomem_class; |
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109 | +static struct device *bcm2835_gpiomem_dev; |
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110 | +static struct bcm2835_gpiomem_instance *inst; |
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111 | + |
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112 | + |
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113 | +/**************************************************************************** |
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114 | +* |
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115 | +* GPIO mem chardev file ops |
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116 | +* |
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117 | +***************************************************************************/ |
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118 | + |
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119 | +static int bcm2835_gpiomem_open(struct inode *inode, struct file *file) |
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120 | +{ |
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121 | + int dev = iminor(inode); |
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122 | + int ret = 0; |
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123 | + |
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124 | + if (dev != DEVICE_MINOR) { |
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125 | + dev_err(inst->dev, "Unknown minor device: %d", dev); |
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126 | + ret = -ENXIO; |
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127 | + } |
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128 | + return ret; |
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129 | +} |
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130 | + |
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131 | +static int bcm2835_gpiomem_release(struct inode *inode, struct file *file) |
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132 | +{ |
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133 | + int dev = iminor(inode); |
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134 | + int ret = 0; |
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135 | + |
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136 | + if (dev != DEVICE_MINOR) { |
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137 | + dev_err(inst->dev, "Unknown minor device %d", dev); |
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138 | + ret = -ENXIO; |
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139 | + } |
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140 | + return ret; |
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141 | +} |
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142 | + |
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143 | +static const struct vm_operations_struct bcm2835_gpiomem_vm_ops = { |
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144 | +#ifdef CONFIG_HAVE_IOREMAP_PROT |
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145 | + .access = generic_access_phys |
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146 | +#endif |
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147 | +}; |
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148 | + |
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149 | +static int bcm2835_gpiomem_mmap(struct file *file, struct vm_area_struct *vma) |
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150 | +{ |
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151 | + /* Ignore what the user says - they're getting the GPIO regs |
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152 | + whether they like it or not! */ |
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153 | + unsigned long gpio_page = inst->gpio_regs_phys >> PAGE_SHIFT; |
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154 | + |
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155 | + vma->vm_page_prot = phys_mem_access_prot(file, gpio_page, |
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156 | + PAGE_SIZE, |
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157 | + vma->vm_page_prot); |
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158 | + vma->vm_ops = &bcm2835_gpiomem_vm_ops; |
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159 | + if (remap_pfn_range(vma, vma->vm_start, |
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160 | + gpio_page, |
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161 | + PAGE_SIZE, |
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162 | + vma->vm_page_prot)) { |
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163 | + return -EAGAIN; |
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164 | + } |
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165 | + return 0; |
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166 | +} |
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167 | + |
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168 | +static const struct file_operations |
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169 | +bcm2835_gpiomem_fops = { |
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170 | + .owner = THIS_MODULE, |
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171 | + .open = bcm2835_gpiomem_open, |
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172 | + .release = bcm2835_gpiomem_release, |
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173 | + .mmap = bcm2835_gpiomem_mmap, |
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174 | +}; |
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175 | + |
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176 | + |
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177 | + /**************************************************************************** |
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178 | +* |
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179 | +* Probe and remove functions |
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180 | +* |
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181 | +***************************************************************************/ |
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182 | + |
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183 | + |
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184 | +static int bcm2835_gpiomem_probe(struct platform_device *pdev) |
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185 | +{ |
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186 | + int err; |
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187 | + void *ptr_err; |
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188 | + struct device *dev = &pdev->dev; |
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189 | + struct resource *ioresource; |
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190 | + |
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191 | + /* Allocate buffers and instance data */ |
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192 | + |
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193 | + inst = kzalloc(sizeof(struct bcm2835_gpiomem_instance), GFP_KERNEL); |
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194 | + |
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195 | + if (!inst) { |
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196 | + err = -ENOMEM; |
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197 | + goto failed_inst_alloc; |
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198 | + } |
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199 | + |
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200 | + inst->dev = dev; |
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201 | + |
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202 | + ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
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203 | + if (ioresource) { |
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204 | + inst->gpio_regs_phys = ioresource->start; |
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205 | + } else { |
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206 | + dev_err(inst->dev, "failed to get IO resource"); |
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207 | + err = -ENOENT; |
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208 | + goto failed_get_resource; |
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209 | + } |
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210 | + |
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211 | + /* Create character device entries */ |
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212 | + |
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213 | + err = alloc_chrdev_region(&bcm2835_gpiomem_devid, |
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214 | + DEVICE_MINOR, 1, DEVICE_NAME); |
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215 | + if (err != 0) { |
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216 | + dev_err(inst->dev, "unable to allocate device number"); |
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217 | + goto failed_alloc_chrdev; |
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218 | + } |
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219 | + cdev_init(&bcm2835_gpiomem_cdev, &bcm2835_gpiomem_fops); |
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220 | + bcm2835_gpiomem_cdev.owner = THIS_MODULE; |
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221 | + err = cdev_add(&bcm2835_gpiomem_cdev, bcm2835_gpiomem_devid, 1); |
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222 | + if (err != 0) { |
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223 | + dev_err(inst->dev, "unable to register device"); |
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224 | + goto failed_cdev_add; |
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225 | + } |
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226 | + |
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227 | + /* Create sysfs entries */ |
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228 | + |
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229 | + bcm2835_gpiomem_class = class_create(THIS_MODULE, DEVICE_NAME); |
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230 | + ptr_err = bcm2835_gpiomem_class; |
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231 | + if (IS_ERR(ptr_err)) |
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232 | + goto failed_class_create; |
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233 | + |
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234 | + bcm2835_gpiomem_dev = device_create(bcm2835_gpiomem_class, NULL, |
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235 | + bcm2835_gpiomem_devid, NULL, |
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236 | + "gpiomem"); |
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237 | + ptr_err = bcm2835_gpiomem_dev; |
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238 | + if (IS_ERR(ptr_err)) |
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239 | + goto failed_device_create; |
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240 | + |
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241 | + dev_info(inst->dev, "Initialised: Registers at 0x%08lx", |
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242 | + inst->gpio_regs_phys); |
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243 | + |
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244 | + return 0; |
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245 | + |
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246 | +failed_device_create: |
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247 | + class_destroy(bcm2835_gpiomem_class); |
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248 | +failed_class_create: |
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249 | + cdev_del(&bcm2835_gpiomem_cdev); |
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250 | + err = PTR_ERR(ptr_err); |
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251 | +failed_cdev_add: |
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252 | + unregister_chrdev_region(bcm2835_gpiomem_devid, 1); |
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253 | +failed_alloc_chrdev: |
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254 | +failed_get_resource: |
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255 | + kfree(inst); |
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256 | +failed_inst_alloc: |
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257 | + dev_err(inst->dev, "could not load bcm2835_gpiomem"); |
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258 | + return err; |
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259 | +} |
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260 | + |
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261 | +static int bcm2835_gpiomem_remove(struct platform_device *pdev) |
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262 | +{ |
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263 | + struct device *dev = inst->dev; |
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264 | + |
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265 | + kfree(inst); |
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266 | + device_destroy(bcm2835_gpiomem_class, bcm2835_gpiomem_devid); |
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267 | + class_destroy(bcm2835_gpiomem_class); |
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268 | + cdev_del(&bcm2835_gpiomem_cdev); |
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269 | + unregister_chrdev_region(bcm2835_gpiomem_devid, 1); |
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270 | + |
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271 | + dev_info(dev, "GPIO mem driver removed - OK"); |
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272 | + return 0; |
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273 | +} |
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274 | + |
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275 | + /**************************************************************************** |
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276 | +* |
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277 | +* Register the driver with device tree |
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278 | +* |
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279 | +***************************************************************************/ |
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280 | + |
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281 | +static const struct of_device_id bcm2835_gpiomem_of_match[] = { |
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282 | + {.compatible = "brcm,bcm2835-gpiomem",}, |
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283 | + { /* sentinel */ }, |
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284 | +}; |
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285 | + |
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286 | +MODULE_DEVICE_TABLE(of, bcm2835_gpiomem_of_match); |
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287 | + |
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288 | +static struct platform_driver bcm2835_gpiomem_driver = { |
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289 | + .probe = bcm2835_gpiomem_probe, |
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290 | + .remove = bcm2835_gpiomem_remove, |
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291 | + .driver = { |
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292 | + .name = DRIVER_NAME, |
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293 | + .owner = THIS_MODULE, |
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294 | + .of_match_table = bcm2835_gpiomem_of_match, |
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295 | + }, |
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296 | +}; |
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297 | + |
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298 | +module_platform_driver(bcm2835_gpiomem_driver); |
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299 | + |
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300 | +MODULE_ALIAS("platform:gpiomem-bcm2835"); |
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301 | +MODULE_LICENSE("GPL"); |
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302 | +MODULE_DESCRIPTION("gpiomem driver for accessing GPIO from userspace"); |
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303 | +MODULE_AUTHOR("Luke Wren <luke@raspberrypi.org>"); |