spi: enable spi_board_info to be registered after spi_master

From b42755bb2e4e2162951bf6544e9fce82452eab5e Mon Sep 17 00:00:00 2001

Hi All,

Pls review this patch. thanks,

-Feng

Changelog:
       v4/5:
          * Abstract a spi_match_master_to_boardinfo() which will be called in scanning master/boardinfo list, suggested by Grant also.
       v3:
          * As suggested by Grant, use one lock to protect the match between spi_master and spi board info
       v2:
          * fix a typo in looping scan_masterlist()
          * fix one race condition found by Grant

From b42755bb2e4e2162951bf6544e9fce82452eab5e Mon Sep 17 00:00:00 2001
From: Feng Tang <[email protected]>
Date: Tue, 27 Jul 2010 17:15:05 +0800
Subject: [PATCH] spi: enable spi_board_info to be registered after spi_master

Currently spi_register_board_info() has to be called before its related spi_master be registered, otherwise these board info will be just ignored.

This patch will remove this order limit, it adds a global spi master list like the existing global board info listr. Whenever a board info or a spi_master is registered, the spi master list or board info list will be scanned, and a new spi device will be created if there is a master-board info match.

Cc David Brownell <[email protected]>

Cc Grant Likely <grant.likely-s3s/[email protected]>

Signed-off-by Feng Tang <[email protected]>

---
 drivers/spi/spi.c       |   86 ++++++++++++++++++++++++---------------------- include/linux/spi/spi.h |    3 ++

 2 files changed, 48 insertions(+), 41 deletions(-)

drivers/spi/spi.c +21 -7

index b3a1f92..a868cc0 100644
@@ -27,11 +27,6 @@
  #include <linux/mod_devicetable.h>
  #include <linux/spi/spi.h>
 
-
-/* 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)
  {
        struct spi_device       *spi = to_spi_device(dev);

@@ -196,11 +191,16 @@ EXPORT_SYMBOL_GPL(spi_register_driver);
 
  struct boardinfo {
        struct list_head        list;
-       unsigned                n_board_info;
-       struct spi_board_info   board_info[0];
+       struct spi_board_info   board_info;
  };
 
  static LIST_HEAD(board_list);
+static LIST_HEAD(spi_master_list);
+
+/*
+ * Used to protect add/del opertion for board_info list and
+ * spi_master list, and their matching process
+ */
  static DEFINE_MUTEX(board_lock);
 
  /**

@@ -365,6 +365,20 @@ struct spi_device *spi_new_device(struct spi_master *master,
  }
  EXPORT_SYMBOL_GPL(spi_new_device);
 
+static void spi_match_master_to_boardinfo(struct spi_master *master,
+                               struct spi_board_info *bi)
+{
+       struct spi_device *dev;
+
+       if (master->bus_num != bi->bus_num)
+               return;
+
+       dev = spi_new_device(master, bi);
+       if (!dev)
+               dev_err(master->dev.parent, "can't create new device for %s\n",
+                       bi->modalias);
+}
+
  /**
  * spi_register_board_info - register SPI devices for a given board
  * @info: array of chip descriptors

@@ -387,43 +401,25 @@ EXPORT_SYMBOL_GPL(spi_new_device);

 int __init
 spi_register_board_info(struct spi_board_info const *info, unsigned n) {
-       struct boardinfo        *bi;
+       struct boardinfo *bi;
+       int i;

-       bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
+       bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
       if (!bi)
               return -ENOMEM;
-       bi->n_board_info = n;
-       memcpy(bi->board_info, info, n * sizeof *info);

drivers/spi/spi.c +8 -26

-
-       mutex_lock(&board_lock);
-       list_add_tail(&bi->list, &board_list);
-       mutex_unlock(&board_lock);
-       return 0;
-}
 
-/* FIXME someone should add support for a __setup("spi", ...) that
- * creates board info from kernel command lines
- */
+       for (i = 0; i < n; i++, bi++, info++) {
+               struct spi_master *master;
 
-static void scan_boardinfo(struct spi_master *master)
-{
-       struct boardinfo        *bi;
-
-       mutex_lock(&board_lock);
-       list_for_each_entry(bi, &board_list, list) {
-               struct spi_board_info   *chip = bi->board_info;
-               unsigned                n;
-
-               for (n = bi->n_board_info; n > 0; n--, chip++) {
-                       if (chip->bus_num != master->bus_num)
-                               continue;
-                       /* NOTE: this relies on spi_new_device to
-                        * issue diagnostics when given bogus inputs
-                        */
-                       (void) spi_new_device(master, chip);
-               }
+               memcpy(&bi->board_info, info, sizeof(*info));
+               mutex_lock(&board_lock);
+               list_add_tail(&bi->list, &board_list);
+               list_for_each_entry(master, &spi_master_list, list)
+                       spi_match_master_to_boardinfo(master, &bi->board_info);
+               mutex_unlock(&board_lock);

       }
-       mutex_unlock(&board_lock);
+
+       return 0;
 }

 /*-------------------------------------------------------------------------*/

drivers/spi/spi.c +7 -2

@@ -506,6 +502,7 @@ int spi_register_master(struct spi_master *master)
  {
        static atomic_t         dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
        struct device           *dev = master->dev.parent;
+       struct boardinfo        *bi;
        int                     status = -ENODEV;
        int                     dynamic = 0;
 

@@ -537,15 +534,18 @@ int spi_register_master(struct spi_master *master)
        dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
                        dynamic ? " (dynamic)" : "");
 
-       /* populate children from any spi device tables */
-       scan_boardinfo(master);
+       mutex_lock(&board_lock);
+       list_add_tail(&master->list, &spi_master_list);
+       list_for_each_entry(bi, &board_list, list)
+               spi_match_master_to_boardinfo(master, &bi->board_info);
+       mutex_unlock(&board_lock);
+
        status = 0;

 done:
       return status;
 }
 EXPORT_SYMBOL_GPL(spi_register_master);

-
 static int __unregister(struct device *dev, void *master_dev) {
       /* note: before about 2.6.14-rc1 this would corrupt memory: */

drivers/spi/spi.c +4 -0

@@ -568,6 +568,10 @@ void spi_unregister_master(struct spi_master *master)
  {
        int dummy;
 
+       mutex_lock(&board_lock);
+       list_del(&master->list);
+       mutex_unlock(&board_lock);
+
        dummy = device_for_each_child(master->dev.parent, &master->dev,
                                        __unregister);
        device_unregister(&master->dev);

include/linux/spi/spi.h +3 -1

index af56071..f4a29b6 100644
@@ -204,6 +204,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  /**
  * struct spi_master - interface to SPI master controller
  * @dev: device interface to this driver
+ * @list: link with the global spi_master list
  * @bus_num: board-specific (and often SOC-specific) identifier for a
  *     given SPI controller.
  * @num_chipselect: chipselects are used to distinguish individual

@@ -235,6 +236,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  struct spi_master {
        struct device   dev;
 
+       struct list_head list;
+
        /* other than negative (== assign one dynamically), bus_num is fully
         * board-specific.  usually that simplifies to being SOC-specific.
         * example:  one SOC has three SPI controllers, numbered 0..2,
--

1.7.0.4