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.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 47 insertions, 41 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b5a78a1f4421..0845cd4c5155 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -29,11 +29,6 @@
 #include <linux/spi/spi.h>
 #include <linux/of_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);
@@ -202,11 +197,16 @@ 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);
 
 /**
@@ -371,6 +371,20 @@ 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
@@ -393,43 +407,25 @@ 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);
 
-        mutex_lock(&board_lock);
-        list_add_tail(&bi->list, &board_list);
-        mutex_unlock(&board_lock);
-        return 0;
-}
+        for (i = 0; i < n; i++, bi++, info++) {
+                struct spi_master *master;
 
-/* FIXME someone should add support for a __setup("spi", ...) that
- * creates board info from kernel command lines
- */
-
-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;
 }
 
 /*-------------------------------------------------------------------------*/
@@ -512,6 +508,7 @@ 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;
 
@@ -547,8 +544,12 @@ 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;
 
         /* Register devices from the device tree */
@@ -579,7 +580,12 @@ void spi_unregister_master(struct spi_master *master)
 {
         int dummy;
 
-        dummy = device_for_each_child(&master->dev, NULL, __unregister);
+        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);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);