[PATCH] spi: add spi_driver to SPI framework

This is a refresh of the "Simple SPI Framework" found in 2.6.15-rc3-mm1
which makes the following changes:

  * There's now a "struct spi_driver".  This increase the footprint
    of the core a bit, since it now includes code to do what the driver
    core was previously handling directly.  Documentation and comments
    were updated to match.

  * spi_alloc_master() now does class_device_initialize(), so it can
    at least be refcounted before spi_register_master().  To match,
    spi_register_master() switched over to class_device_add().

  * States explicitly that after transfer errors, spi_devices will be
    deselected.  We want fault recovery procedures to work the same
    for all controller drivers.

  * Minor tweaks:  controller_data no longer points to readonly data;
    prevent some potential cast-from-null bugs with container_of calls;
    clarifies some existing kerneldoc,

And a few small cleanups.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 86 insertions, 32 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 7cd356b17644..2ecb86cb3689 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -26,13 +26,9 @@
 #include <linux/spi/spi.h>
 
 
-/* SPI bustype and spi_master class are registered during early boot,
- * usually before board init code provides the SPI device tables, and
- * are available later when driver init code needs them.
- *
- * Drivers for SPI devices started out like those for platform bus
- * devices.  But both have changed in 2.6.15; maybe this should get
- * an "spi_driver" structure at some point (not currently needed)
+/* SPI bustype and spi_master class are registered after board init code
+ * provides the SPI device tables, ensuring that both are present by the
+ * time controller driver registration causes spi_devices to "enumerate".
  */
 static void spidev_release(struct device *dev)
 {
@@ -83,10 +79,7 @@ static int spi_uevent(struct device *dev, char **envp, int num_envp,
 
 #ifdef  CONFIG_PM
 
-/* Suspend/resume in "struct device_driver" don't really need that
- * strange third parameter, so we just make it a constant and expect
- * SPI drivers to ignore it just like most platform drivers do.
- *
+/*
  * NOTE:  the suspend() method for an spi_master controller driver
  * should verify that all its child devices are marked as suspended;
  * suspend requests delivered through sysfs power/state files don't
@@ -94,13 +87,14 @@ static int spi_uevent(struct device *dev, char **envp, int num_envp,
  */
 static int spi_suspend(struct device *dev, pm_message_t message)
 {
-        int     value;
+        int                     value;
+        struct spi_driver       *drv = to_spi_driver(dev->driver);
 
-        if (!dev->driver || !dev->driver->suspend)
+        if (!drv || !drv->suspend)
                 return 0;
 
         /* suspend will stop irqs and dma; no more i/o */
-        value = dev->driver->suspend(dev, message);
+        value = drv->suspend(to_spi_device(dev), message);
         if (value == 0)
                 dev->power.power_state = message;
         return value;
@@ -108,13 +102,14 @@ static int spi_suspend(struct device *dev, pm_message_t message)
 
 static int spi_resume(struct device *dev)
 {
-        int     value;
+        int                     value;
+        struct spi_driver       *drv = to_spi_driver(dev->driver);
 
-        if (!dev->driver || !dev->driver->resume)
+        if (!drv || !drv->resume)
                 return 0;
 
         /* resume may restart the i/o queue */
-        value = dev->driver->resume(dev);
+        value = drv->resume(to_spi_device(dev));
         if (value == 0)
                 dev->power.power_state = PMSG_ON;
         return value;
@@ -135,6 +130,41 @@ struct bus_type spi_bus_type = {
 };
 EXPORT_SYMBOL_GPL(spi_bus_type);
 
+
+static int spi_drv_probe(struct device *dev)
+{
+        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
+
+        return sdrv->probe(to_spi_device(dev));
+}
+
+static int spi_drv_remove(struct device *dev)
+{
+        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
+
+        return sdrv->remove(to_spi_device(dev));
+}
+
+static void spi_drv_shutdown(struct device *dev)
+{
+        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
+
+        sdrv->shutdown(to_spi_device(dev));
+}
+
+int spi_register_driver(struct spi_driver *sdrv)
+{
+        sdrv->driver.bus = &spi_bus_type;
+        if (sdrv->probe)
+                sdrv->driver.probe = spi_drv_probe;
+        if (sdrv->remove)
+                sdrv->driver.remove = spi_drv_remove;
+        if (sdrv->shutdown)
+                sdrv->driver.shutdown = spi_drv_shutdown;
+        return driver_register(&sdrv->driver);
+}
+EXPORT_SYMBOL_GPL(spi_register_driver);
+
 /*-------------------------------------------------------------------------*/
 
 /* SPI devices should normally not be created by SPI device drivers; that
@@ -208,13 +238,15 @@ spi_new_device(struct spi_master *master, struct spi_board_info *chip)
         if (status < 0) {
                 dev_dbg(dev, "can't %s %s, status %d\n",
                                 "add", proxy->dev.bus_id, status);
-fail:
-                class_device_put(&master->cdev);
-                kfree(proxy);
-                return NULL;
+                goto fail;
         }
         dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
         return proxy;
+
+fail:
+        class_device_put(&master->cdev);
+        kfree(proxy);
+        return NULL;
 }
 EXPORT_SYMBOL_GPL(spi_new_device);
 
@@ -237,11 +269,11 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
 {
         struct boardinfo        *bi;
 
-        bi = kmalloc (sizeof (*bi) + n * sizeof (*info), GFP_KERNEL);
+        bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
         if (!bi)
                 return -ENOMEM;
         bi->n_board_info = n;
-        memcpy(bi->board_info, info, n * sizeof (*info));
+        memcpy(bi->board_info, info, n * sizeof *info);
 
         down(&board_lock);
         list_add_tail(&bi->list, &board_list);
@@ -330,6 +362,7 @@ spi_alloc_master(struct device *dev, unsigned size)
         if (!master)
                 return NULL;
 
+        class_device_initialize(&master->cdev);
         master->cdev.class = &spi_master_class;
         master->cdev.dev = get_device(dev);
         class_set_devdata(&master->cdev, &master[1]);
@@ -366,7 +399,7 @@ spi_register_master(struct spi_master *master)
         /* convention:  dynamically assigned bus IDs count down from the max */
         if (master->bus_num == 0) {
                 master->bus_num = atomic_dec_return(&dyn_bus_id);
-                dynamic = 0;
+                dynamic = 1;
         }
 
         /* register the device, then userspace will see it.
@@ -374,11 +407,9 @@ spi_register_master(struct spi_master *master)
          */
         snprintf(master->cdev.class_id, sizeof master->cdev.class_id,
                 "spi%u", master->bus_num);
-        status = class_device_register(&master->cdev);
-        if (status < 0) {
-                class_device_put(&master->cdev);
+        status = class_device_add(&master->cdev);
+        if (status < 0)
                 goto done;
-        }
         dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id,
                         dynamic ? " (dynamic)" : "");
 
@@ -491,6 +522,7 @@ static u8	*buf;
  * This performs a half duplex MicroWire style transaction with the
  * device, sending txbuf and then reading rxbuf.  The return value
  * is zero for success, else a negative errno status code.
+ * This call may only be used from a context that may sleep.
  *
  * Parameters to this routine are always copied using a small buffer,
  * large transfers should use use spi_{async,sync}() calls with
@@ -553,16 +585,38 @@ EXPORT_SYMBOL_GPL(spi_write_then_read);
 
 static int __init spi_init(void)
 {
+        int     status;
+
         buf = kmalloc(SPI_BUFSIZ, SLAB_KERNEL);
-        if (!buf)
-                return -ENOMEM;
+        if (!buf) {
+                status = -ENOMEM;
+                goto err0;
+        }
+
+        status = bus_register(&spi_bus_type);
+        if (status < 0)
+                goto err1;
 
-        bus_register(&spi_bus_type);
-        class_register(&spi_master_class);
+        status = class_register(&spi_master_class);
+        if (status < 0)
+                goto err2;
         return 0;
+
+err2:
+        bus_unregister(&spi_bus_type);
+err1:
+        kfree(buf);
+        buf = NULL;
+err0:
+        return status;
 }
+
 /* board_info is normally registered in arch_initcall(),
  * but even essential drivers wait till later
+ *
+ * REVISIT only boardinfo really needs static linking. the rest (device and
+ * driver registration) _could_ be dynamically linked (modular) ... costs
+ * include needing to have boardinfo data structures be much more public.
  */
 subsys_initcall(spi_init);