drivers/mfd/ab8500-spi.c

   1 /*
   2  * Copyright (C) ST-Ericsson SA 2010
   3  *
   4  * License Terms: GNU General Public License v2
   5  * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/mfd/ab8500.h>
  15
  16 /*
  17  * This funtion writes to any AB8500 registers using
  18  * SPI protocol &  before it writes it packs the data
  19  * in the below 24 bit frame format
  20  *
  21  *       *|------------------------------------|
  22  *       *| 23|22...18|17.......10|9|8|7......0|
  23  *       *| r/w  bank       adr          data  |
  24  *       * ------------------------------------
  25  *
  26  * This function shouldn't be called from interrupt
  27  * context
  28  */
  29 static int ab8500_spi_write(struct ab8500 *ab8500, u16 addr, u8 data)
  30 {
  31         struct spi_device *spi = container_of(ab8500->dev, struct spi_device,
  32                                               dev);
  33         unsigned long spi_data = addr << 10 | data;
  34         struct spi_transfer xfer;
  35         struct spi_message msg;
  36
  37         ab8500->tx_buf[0] = spi_data;
  38         ab8500->rx_buf[0] = 0;
  39
  40         xfer.tx_buf     = ab8500->tx_buf;
  41         xfer.rx_buf     = NULL;
  42         xfer.len        = sizeof(unsigned long);
  43
  44         spi_message_init(&msg);
  45         spi_message_add_tail(&xfer, &msg);
  46
  47         return spi_sync(spi, &msg);
  48 }
  49
  50 static int ab8500_spi_read(struct ab8500 *ab8500, u16 addr)
  51 {
  52         struct spi_device *spi = container_of(ab8500->dev, struct spi_device,
  53                                               dev);
  54         unsigned long spi_data = 1 << 23 | addr << 10;
  55         struct spi_transfer xfer;
  56         struct spi_message msg;
  57         int ret;
  58
  59         ab8500->tx_buf[0] = spi_data;
  60         ab8500->rx_buf[0] = 0;
  61
  62         xfer.tx_buf     = ab8500->tx_buf;
  63         xfer.rx_buf     = ab8500->rx_buf;
  64         xfer.len        = sizeof(unsigned long);
  65
  66         spi_message_init(&msg);
  67         spi_message_add_tail(&xfer, &msg);
  68
  69         ret = spi_sync(spi, &msg);
  70         if (!ret)
  71                 /*
  72                  * Only the 8 lowermost bytes are
  73                  * defined with value, the rest may
  74                  * vary depending on chip/board noise.
  75                  */
  76                 ret = ab8500->rx_buf[0] & 0xFFU;
  77
  78         return ret;
  79 }
  80
  81 static int __devinit ab8500_spi_probe(struct spi_device *spi)
  82 {
  83         struct ab8500 *ab8500;
  84         int ret;
  85
  86         spi->bits_per_word = 24;
  87         ret = spi_setup(spi);
  88         if (ret < 0)
  89                 return ret;
  90
  91         ab8500 = kzalloc(sizeof *ab8500, GFP_KERNEL);
  92         if (!ab8500)
  93                 return -ENOMEM;
  94
  95         ab8500->dev = &spi->dev;
  96         ab8500->irq = spi->irq;
  97
  98         ab8500->read = ab8500_spi_read;
  99         ab8500->write = ab8500_spi_write;
 100
 101         spi_set_drvdata(spi, ab8500);
 102
 103         ret = ab8500_init(ab8500);
 104         if (ret)
 105                 kfree(ab8500);
 106
 107         return ret;
 108 }
 109
 110 static int __devexit ab8500_spi_remove(struct spi_device *spi)
 111 {
 112         struct ab8500 *ab8500 = spi_get_drvdata(spi);
 113
 114         ab8500_exit(ab8500);
 115         kfree(ab8500);
 116
 117         return 0;
 118 }
 119
 120 static struct spi_driver ab8500_spi_driver = {
 121         .driver = {
 122                 .name = "ab8500-spi",
 123                 .owner = THIS_MODULE,
 124         },
 125         .probe  = ab8500_spi_probe,
 126         .remove = __devexit_p(ab8500_spi_remove)
 127 };
 128
 129 static int __init ab8500_spi_init(void)
 130 {
 131         return spi_register_driver(&ab8500_spi_driver);
 132 }
 133 subsys_initcall(ab8500_spi_init);
 134
 135 static void __exit ab8500_spi_exit(void)
 136 {
 137         spi_unregister_driver(&ab8500_spi_driver);
 138 }
 139 module_exit(ab8500_spi_exit);
 140
 141 MODULE_AUTHOR("Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com");
 142 MODULE_DESCRIPTION("AB8500 SPI");
 143 MODULE_LICENSE("GPL v2");