drivers/of/of_spi.c

   1 /*
   2  * SPI OF support routines
   3  * Copyright (C) 2008 Secret Lab Technologies Ltd.
   4  *
   5  * Support routines for deriving SPI device attachments from the device
   6  * tree.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/of.h>
  11 #include <linux/device.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/of_irq.h>
  14 #include <linux/of_spi.h>
  15
  16 /**
  17  * of_register_spi_devices - Register child devices onto the SPI bus
  18  * @master:     Pointer to spi_master device
  19  *
  20  * Registers an spi_device for each child node of master node which has a 'reg'
  21  * property.
  22  */
  23 void of_register_spi_devices(struct spi_master *master)
  24 {
  25         struct spi_device *spi;
  26         struct device_node *nc;
  27         const __be32 *prop;
  28         int rc;
  29         int len;
  30
  31         if (!master->dev.of_node)
  32                 return;
  33
  34         for_each_child_of_node(master->dev.of_node, nc) {
  35                 /* Alloc an spi_device */
  36                 spi = spi_alloc_device(master);
  37                 if (!spi) {
  38                         dev_err(&master->dev, "spi_device alloc error for %s\n",
  39                                 nc->full_name);
  40                         spi_dev_put(spi);
  41                         continue;
  42                 }
  43
  44                 /* Select device driver */
  45                 if (of_modalias_node(nc, spi->modalias,
  46                                      sizeof(spi->modalias)) < 0) {
  47                         dev_err(&master->dev, "cannot find modalias for %s\n",
  48                                 nc->full_name);
  49                         spi_dev_put(spi);
  50                         continue;
  51                 }
  52
  53                 /* Device address */
  54                 prop = of_get_property(nc, "reg", &len);
  55                 if (!prop || len < sizeof(*prop)) {
  56                         dev_err(&master->dev, "%s has no 'reg' property\n",
  57                                 nc->full_name);
  58                         spi_dev_put(spi);
  59                         continue;
  60                 }
  61                 spi->chip_select = be32_to_cpup(prop);
  62
  63                 /* Mode (clock phase/polarity/etc.) */
  64                 if (of_find_property(nc, "spi-cpha", NULL))
  65                         spi->mode |= SPI_CPHA;
  66                 if (of_find_property(nc, "spi-cpol", NULL))
  67                         spi->mode |= SPI_CPOL;
  68                 if (of_find_property(nc, "spi-cs-high", NULL))
  69                         spi->mode |= SPI_CS_HIGH;
  70
  71                 /* Device speed */
  72                 prop = of_get_property(nc, "spi-max-frequency", &len);
  73                 if (!prop || len < sizeof(*prop)) {
  74                         dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
  75                                 nc->full_name);
  76                         spi_dev_put(spi);
  77                         continue;
  78                 }
  79                 spi->max_speed_hz = be32_to_cpup(prop);
  80
  81                 /* IRQ */
  82                 spi->irq = irq_of_parse_and_map(nc, 0);
  83
  84                 /* Store a pointer to the node in the device structure */
  85                 of_node_get(nc);
  86                 spi->dev.of_node = nc;
  87
  88                 /* Register the new device */
  89                 request_module(spi->modalias);
  90                 rc = spi_add_device(spi);
  91                 if (rc) {
  92                         dev_err(&master->dev, "spi_device register error %s\n",
  93                                 nc->full_name);
  94                         spi_dev_put(spi);
  95                 }
  96
  97         }
  98 }
  99 EXPORT_SYMBOL(of_register_spi_devices);