scoutos / scout_gumstix / encoder / encoder.c @ 280c6899
History | View | Annotate | Download (4.95 KB)
| 1 | 83163372 | Tom Mullins | #include <linux/init.h> |
|---|---|---|---|
| 2 | #include <linux/module.h> |
||
| 3 | #include <linux/fs.h> |
||
| 4 | #include <linux/cdev.h> |
||
| 5 | #include <linux/slab.h> |
||
| 6 | #include <linux/device.h> |
||
| 7 | #include <linux/semaphore.h> |
||
| 8 | f024710b | Tom Mullins | #include <linux/interrupt.h> |
| 9 | #include <linux/gpio.h> |
||
| 10 | 280c6899 | Tom Mullins | #include <asm/atomic.h> |
| 11 | 83163372 | Tom Mullins | |
| 12 | MODULE_AUTHOR("Tom Mullins");
|
||
| 13 | MODULE_LICENSE("GPL");
|
||
| 14 | |||
| 15 | #define N_ENCODERS 4 |
||
| 16 | f024710b | Tom Mullins | const int enc_pins[N_ENCODERS][2] = {{78, 79}, {80, 81}, {82, 83}, {84, 85}}; |
| 17 | 83163372 | Tom Mullins | struct class *enc_class = NULL; |
| 18 | |||
| 19 | 280c6899 | Tom Mullins | struct encoder_device
|
| 20 | 83163372 | Tom Mullins | {
|
| 21 | struct device *device;
|
||
| 22 | 280c6899 | Tom Mullins | int pins[2]; |
| 23 | f024710b | Tom Mullins | int irq[2]; |
| 24 | 83163372 | Tom Mullins | int status;
|
| 25 | f024710b | Tom Mullins | atomic_t value; |
| 26 | 83163372 | Tom Mullins | dev_t dev; |
| 27 | } |
||
| 28 | encs[N_ENCODERS]; |
||
| 29 | |||
| 30 | 280c6899 | Tom Mullins | static ssize_t enc_show(struct device *dev, struct device_attribute *attr, |
| 31 | char *buf);
|
||
| 32 | static ssize_t enc_store(struct device *dev, struct device_attribute *attr, |
||
| 33 | const char *buf, size_t count); |
||
| 34 | static void enc_free(struct encoder_device *enc); |
||
| 35 | static int enc_init(dev_t dev, struct encoder_device *enc, const int *pins); |
||
| 36 | 83163372 | Tom Mullins | |
| 37 | 280c6899 | Tom Mullins | DEVICE_ATTR(ticks, S_IWUSR | S_IRUGO, enc_show, enc_store); |
| 38 | 83163372 | Tom Mullins | |
| 39 | 280c6899 | Tom Mullins | static ssize_t enc_show(struct device *dev, struct device_attribute *attr, |
| 40 | char *buf)
|
||
| 41 | 83163372 | Tom Mullins | {
|
| 42 | 280c6899 | Tom Mullins | size_t nwritten; |
| 43 | struct encoder_device *enc = dev_get_drvdata(dev);
|
||
| 44 | nwritten = scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&enc->value));
|
||
| 45 | return nwritten;
|
||
| 46 | 83163372 | Tom Mullins | } |
| 47 | |||
| 48 | 280c6899 | Tom Mullins | static ssize_t enc_store(struct device *dev, struct device_attribute *attr, |
| 49 | const char *buf, size_t count) |
||
| 50 | 83163372 | Tom Mullins | {
|
| 51 | char *end;
|
||
| 52 | 280c6899 | Tom Mullins | struct encoder_device *enc = dev_get_drvdata(dev);
|
| 53 | atomic_set(&enc->value, simple_strtol(buf, &end, 10));
|
||
| 54 | 83163372 | Tom Mullins | return count;
|
| 55 | } |
||
| 56 | |||
| 57 | 280c6899 | Tom Mullins | irqreturn_t intA(int irq, void *encp) { |
| 58 | struct encoder_device *enc = encp;
|
||
| 59 | f024710b | Tom Mullins | int this = gpio_get_value(enc->pins[0]); |
| 60 | int other = gpio_get_value(enc->pins[1]); |
||
| 61 | if (this == other) {
|
||
| 62 | atomic_inc(&enc->value); |
||
| 63 | } else {
|
||
| 64 | atomic_dec(&enc->value); |
||
| 65 | } |
||
| 66 | return IRQ_HANDLED;
|
||
| 67 | } |
||
| 68 | |||
| 69 | 280c6899 | Tom Mullins | irqreturn_t intB(int irq, void *encp) { |
| 70 | struct encoder_device *enc = encp;
|
||
| 71 | f024710b | Tom Mullins | int this = gpio_get_value(enc->pins[1]); |
| 72 | int other = gpio_get_value(enc->pins[0]); |
||
| 73 | if (this == other) {
|
||
| 74 | atomic_dec(&enc->value); |
||
| 75 | } else {
|
||
| 76 | atomic_inc(&enc->value); |
||
| 77 | } |
||
| 78 | return IRQ_HANDLED;
|
||
| 79 | } |
||
| 80 | |||
| 81 | 280c6899 | Tom Mullins | static int enc_init(dev_t dev, struct encoder_device *enc, const int *pins) |
| 82 | 83163372 | Tom Mullins | {
|
| 83 | 280c6899 | Tom Mullins | int i, err;
|
| 84 | 83163372 | Tom Mullins | |
| 85 | // initialize members
|
||
| 86 | enc->dev = dev; |
||
| 87 | enc->status = 0;
|
||
| 88 | |||
| 89 | f024710b | Tom Mullins | // register gpio and interrupts
|
| 90 | for (i = 0; i < 2; i++) { |
||
| 91 | |||
| 92 | enc->pins[i] = pins[i]; |
||
| 93 | |||
| 94 | enc->irq[i] = gpio_to_irq(pins[i]); |
||
| 95 | if (enc->irq[i] < 0) { |
||
| 96 | printk("Error %d requesting irq number for gpio %d\n", enc->irq[i],
|
||
| 97 | enc->pins[i]); |
||
| 98 | return 1; |
||
| 99 | } |
||
| 100 | |||
| 101 | err = gpio_direction_input(enc->pins[i]); |
||
| 102 | if (err < 0) { |
||
| 103 | printk("Error %d setting gpio %d to input\n", err, enc->pins[i]);
|
||
| 104 | return 1; |
||
| 105 | } |
||
| 106 | |||
| 107 | 280c6899 | Tom Mullins | err = request_irq(enc->irq[i], i? intB:intA, 0, "encoder", enc); |
| 108 | f024710b | Tom Mullins | if (err < 0) { |
| 109 | printk("Error %d requesting irq %d\n", err, enc->irq[i]);
|
||
| 110 | return 1; |
||
| 111 | } |
||
| 112 | |||
| 113 | f58d377f | Tom Mullins | err = irq_set_irq_type(enc->irq[i], IRQ_TYPE_EDGE_BOTH); |
| 114 | if (err < 0) { |
||
| 115 | printk("Error %d setting irq %d type\n", err, enc->irq[i]);
|
||
| 116 | return 1; |
||
| 117 | } |
||
| 118 | |||
| 119 | f024710b | Tom Mullins | // TODO the error checking here does not properly clean up after itself
|
| 120 | // TODO perhaps we should use gpio_request? probably not necessary...
|
||
| 121 | } |
||
| 122 | enc->status = 2;
|
||
| 123 | |||
| 124 | return 0; |
||
| 125 | } |
||
| 126 | |||
| 127 | 280c6899 | Tom Mullins | int enc_create_dev(struct encoder_device *enc) { |
| 128 | int err;
|
||
| 129 | f024710b | Tom Mullins | |
| 130 | 83163372 | Tom Mullins | // make file in /dev
|
| 131 | 280c6899 | Tom Mullins | enc->device = device_create(enc_class, NULL, enc->dev, enc, "enc%d", |
| 132 | 83163372 | Tom Mullins | MINOR(enc->dev)); |
| 133 | if (IS_ERR(enc->device))
|
||
| 134 | {
|
||
| 135 | err = PTR_ERR(enc->device); |
||
| 136 | enc->device = NULL;
|
||
| 137 | enc_free(enc); |
||
| 138 | return err;
|
||
| 139 | } |
||
| 140 | f024710b | Tom Mullins | enc->status = 3;
|
| 141 | 83163372 | Tom Mullins | |
| 142 | 280c6899 | Tom Mullins | device_create_file(enc->device, &dev_attr_ticks); |
| 143 | // TODO error check
|
||
| 144 | enc->status = 4;
|
||
| 145 | |||
| 146 | 83163372 | Tom Mullins | return 0; |
| 147 | } |
||
| 148 | |||
| 149 | 280c6899 | Tom Mullins | static void enc_free(struct encoder_device *enc) |
| 150 | 83163372 | Tom Mullins | {
|
| 151 | switch (enc->status)
|
||
| 152 | {
|
||
| 153 | 280c6899 | Tom Mullins | case 4: |
| 154 | device_remove_file(enc->device, &dev_attr_ticks); |
||
| 155 | f024710b | Tom Mullins | case 3: |
| 156 | 83163372 | Tom Mullins | device_destroy(enc_class, enc->dev); |
| 157 | enc->device = NULL;
|
||
| 158 | f024710b | Tom Mullins | case 2: |
| 159 | free_irq(enc->irq[0], enc);
|
||
| 160 | free_irq(enc->irq[1], enc);
|
||
| 161 | 83163372 | Tom Mullins | } |
| 162 | enc->status = 0;
|
||
| 163 | } |
||
| 164 | |||
| 165 | static void enc_exit_module(void) |
||
| 166 | {
|
||
| 167 | int i;
|
||
| 168 | for (i = 0; i < N_ENCODERS; i++) |
||
| 169 | {
|
||
| 170 | enc_free(&encs[i]); |
||
| 171 | } |
||
| 172 | if (enc_class) {
|
||
| 173 | class_destroy(enc_class); |
||
| 174 | enc_class = NULL;
|
||
| 175 | } |
||
| 176 | } |
||
| 177 | module_exit(enc_exit_module); |
||
| 178 | |||
| 179 | static int __init enc_init_module(void) |
||
| 180 | {
|
||
| 181 | int i, err;
|
||
| 182 | |||
| 183 | f024710b | Tom Mullins | // initialize enc structures
|
| 184 | for (i = 0; i < N_ENCODERS; i++) { |
||
| 185 | 280c6899 | Tom Mullins | err = enc_init(MKDEV(0, i), &encs[i], enc_pins[i]);
|
| 186 | f024710b | Tom Mullins | if (err)
|
| 187 | {
|
||
| 188 | printk(KERN_WARNING "Error %d initializing encoder %d\n", err, i);
|
||
| 189 | enc_exit_module(); |
||
| 190 | 280c6899 | Tom Mullins | return err;
|
| 191 | f024710b | Tom Mullins | } |
| 192 | } |
||
| 193 | |||
| 194 | 83163372 | Tom Mullins | // register our device class for files in /dev
|
| 195 | enc_class = class_create(THIS_MODULE, "encoder");
|
||
| 196 | if (IS_ERR(enc_class))
|
||
| 197 | {
|
||
| 198 | err = PTR_ERR(enc_class); |
||
| 199 | enc_class = NULL;
|
||
| 200 | printk(KERN_WARNING "Error %d creating device class\n", err);
|
||
| 201 | } |
||
| 202 | else
|
||
| 203 | {
|
||
| 204 | f024710b | Tom Mullins | // create each device
|
| 205 | 83163372 | Tom Mullins | for (i = 0; i < N_ENCODERS; i++) { |
| 206 | f024710b | Tom Mullins | err = enc_create_dev(&encs[i]); |
| 207 | 83163372 | Tom Mullins | if (err)
|
| 208 | {
|
||
| 209 | f024710b | Tom Mullins | printk(KERN_WARNING "Error %d creating enc%d\n", err, i);
|
| 210 | 83163372 | Tom Mullins | enc_exit_module(); |
| 211 | 280c6899 | Tom Mullins | return err;
|
| 212 | 83163372 | Tom Mullins | } |
| 213 | } |
||
| 214 | } |
||
| 215 | |||
| 216 | return 0; |
||
| 217 | } |
||
| 218 | module_init(enc_init_module); |