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