drivers/iio/pressure/zpa2326_spi.c

   1 /*
   2  * Murata ZPA2326 SPI pressure and temperature sensor driver
   3  *
   4  * Copyright (c) 2016 Parrot S.A.
   5  *
   6  * Author: Gregor Boirie <gregor.boirie@parrot.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published by
  10  * the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/regmap.h>
  20 #include <linux/spi/spi.h>
  21 #include <linux/of_device.h>
  22 #include "zpa2326.h"
  23
  24 /*
  25  * read_flag_mask:
  26  *   - address bit 7 must be set to request a register read operation
  27  *   - address bit 6 must be set to request register address auto increment
  28  */
  29 static const struct regmap_config zpa2326_regmap_spi_config = {
  30         .reg_bits       = 8,
  31         .val_bits       = 8,
  32         .writeable_reg  = zpa2326_isreg_writeable,
  33         .readable_reg   = zpa2326_isreg_readable,
  34         .precious_reg   = zpa2326_isreg_precious,
  35         .max_register   = ZPA2326_TEMP_OUT_H_REG,
  36         .read_flag_mask = BIT(7) | BIT(6),
  37         .cache_type     = REGCACHE_NONE,
  38 };
  39
  40 static int zpa2326_probe_spi(struct spi_device *spi)
  41 {
  42         struct regmap *regmap;
  43         int            err;
  44
  45         regmap = devm_regmap_init_spi(spi, &zpa2326_regmap_spi_config);
  46         if (IS_ERR(regmap)) {
  47                 dev_err(&spi->dev, "failed to init registers map");
  48                 return PTR_ERR(regmap);
  49         }
  50
  51         /*
  52          * Enforce SPI slave settings to prevent from DT misconfiguration.
  53          *
  54          * Clock is idle high. Sampling happens on trailing edge, i.e., rising
  55          * edge. Maximum bus frequency is 1 MHz. Registers are 8 bits wide.
  56          */
  57         spi->mode = SPI_MODE_3;
  58         spi->max_speed_hz = min(spi->max_speed_hz, 1000000U);
  59         spi->bits_per_word = 8;
  60         err = spi_setup(spi);
  61         if (err < 0)
  62                 return err;
  63
  64         return zpa2326_probe(&spi->dev, spi_get_device_id(spi)->name,
  65                              spi->irq, ZPA2326_DEVICE_ID, regmap);
  66 }
  67
  68 static int zpa2326_remove_spi(struct spi_device *spi)
  69 {
  70         zpa2326_remove(&spi->dev);
  71
  72         return 0;
  73 }
  74
  75 static const struct spi_device_id zpa2326_spi_ids[] = {
  76         { "zpa2326", 0 },
  77         { },
  78 };
  79 MODULE_DEVICE_TABLE(spi, zpa2326_spi_ids);
  80
  81 #if defined(CONFIG_OF)
  82 static const struct of_device_id zpa2326_spi_matches[] = {
  83         { .compatible = "murata,zpa2326" },
  84         { }
  85 };
  86 MODULE_DEVICE_TABLE(of, zpa2326_spi_matches);
  87 #endif
  88
  89 static struct spi_driver zpa2326_spi_driver = {
  90         .driver = {
  91                 .name           = "zpa2326-spi",
  92                 .of_match_table = of_match_ptr(zpa2326_spi_matches),
  93                 .pm             = ZPA2326_PM_OPS,
  94         },
  95         .probe    = zpa2326_probe_spi,
  96         .remove   = zpa2326_remove_spi,
  97         .id_table = zpa2326_spi_ids,
  98 };
  99 module_spi_driver(zpa2326_spi_driver);
 100
 101 MODULE_AUTHOR("Gregor Boirie <gregor.boirie@parrot.com>");
 102 MODULE_DESCRIPTION("SPI driver for Murata ZPA2326 pressure sensor");
 103 MODULE_LICENSE("GPL v2");