1 /* 2 * Copyright 2008 3 * Guennadi Liakhovetski, DENX Software Engineering, <lg@denx.de> 4 * 5 * This file is subject to the terms and conditions of version 2 of 6 * the GNU General Public License. See the file COPYING in the main 7 * directory of this archive for more details. 8 * 9 * LED driver for the DAC124S085 SPI DAC 10 */ 11 12 #include <linux/leds.h> 13 #include <linux/module.h> 14 #include <linux/mutex.h> 15 #include <linux/slab.h> 16 #include <linux/spinlock.h> 17 #include <linux/workqueue.h> 18 #include <linux/spi/spi.h> 19 20 struct dac124s085_led { 21 struct led_classdev ldev; 22 struct spi_device *spi; 23 int id; 24 int brightness; 25 char name[sizeof("dac124s085-3")]; 26 27 struct mutex mutex; 28 struct work_struct work; 29 spinlock_t lock; 30 }; 31 32 struct dac124s085 { 33 struct dac124s085_led leds[4]; 34 }; 35 36 #define REG_WRITE (0 << 12) 37 #define REG_WRITE_UPDATE (1 << 12) 38 #define ALL_WRITE_UPDATE (2 << 12) 39 #define POWER_DOWN_OUTPUT (3 << 12) 40 41 static void dac124s085_led_work(struct work_struct *work) 42 { 43 struct dac124s085_led *led = container_of(work, struct dac124s085_led, 44 work); 45 u16 word; 46 47 mutex_lock(&led->mutex); 48 word = cpu_to_le16(((led->id) << 14) | REG_WRITE_UPDATE | 49 (led->brightness & 0xfff)); 50 spi_write(led->spi, (const u8 *)&word, sizeof(word)); 51 mutex_unlock(&led->mutex); 52 } 53 54 static void dac124s085_set_brightness(struct led_classdev *ldev, 55 enum led_brightness brightness) 56 { 57 struct dac124s085_led *led = container_of(ldev, struct dac124s085_led, 58 ldev); 59 60 spin_lock(&led->lock); 61 led->brightness = brightness; 62 schedule_work(&led->work); 63 spin_unlock(&led->lock); 64 } 65 66 static int dac124s085_probe(struct spi_device *spi) 67 { 68 struct dac124s085 *dac; 69 struct dac124s085_led *led; 70 int i, ret; 71 72 dac = devm_kzalloc(&spi->dev, sizeof(*dac), GFP_KERNEL); 73 if (!dac) 74 return -ENOMEM; 75 76 spi->bits_per_word = 16; 77 78 for (i = 0; i < ARRAY_SIZE(dac->leds); i++) { 79 led = dac->leds + i; 80 led->id = i; 81 led->brightness = LED_OFF; 82 led->spi = spi; 83 snprintf(led->name, sizeof(led->name), "dac124s085-%d", i); 84 spin_lock_init(&led->lock); 85 INIT_WORK(&led->work, dac124s085_led_work); 86 mutex_init(&led->mutex); 87 led->ldev.name = led->name; 88 led->ldev.brightness = LED_OFF; 89 led->ldev.max_brightness = 0xfff; 90 led->ldev.brightness_set = dac124s085_set_brightness; 91 ret = led_classdev_register(&spi->dev, &led->ldev); 92 if (ret < 0) 93 goto eledcr; 94 } 95 96 spi_set_drvdata(spi, dac); 97 98 return 0; 99 100 eledcr: 101 while (i--) 102 led_classdev_unregister(&dac->leds[i].ldev); 103 104 return ret; 105 } 106 107 static int dac124s085_remove(struct spi_device *spi) 108 { 109 struct dac124s085 *dac = spi_get_drvdata(spi); 110 int i; 111 112 for (i = 0; i < ARRAY_SIZE(dac->leds); i++) { 113 led_classdev_unregister(&dac->leds[i].ldev); 114 cancel_work_sync(&dac->leds[i].work); 115 } 116 117 return 0; 118 } 119 120 static struct spi_driver dac124s085_driver = { 121 .probe = dac124s085_probe, 122 .remove = dac124s085_remove, 123 .driver = { 124 .name = "dac124s085", 125 .owner = THIS_MODULE, 126 }, 127 }; 128 129 module_spi_driver(dac124s085_driver); 130 131 MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>"); 132 MODULE_DESCRIPTION("DAC124S085 LED driver"); 133 MODULE_LICENSE("GPL v2"); 134 MODULE_ALIAS("spi:dac124s085"); 135