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