Merge remote-tracking branch 'spi/topic/doc' into spi-next

2 files changed, 117 insertions, 23 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6a306340dd25..f9e92f535cbb 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -123,6 +123,28 @@ SPI_STATISTICS_SHOW(bytes, "%llu");
 SPI_STATISTICS_SHOW(bytes_rx, "%llu");
 SPI_STATISTICS_SHOW(bytes_tx, "%llu");
 
+#define SPI_STATISTICS_TRANSFER_BYTES_HISTO(index, number)              \
+        SPI_STATISTICS_SHOW_NAME(transfer_bytes_histo##index,           \
+                                 "transfer_bytes_histo_" number,        \
+                                 transfer_bytes_histo[index],  "%lu")
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(0,  "0-1");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(1,  "2-3");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(2,  "4-7");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(3,  "8-15");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(4,  "16-31");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(5,  "32-63");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(6,  "64-127");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(7,  "128-255");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(8,  "256-511");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(9,  "512-1023");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(10, "1024-2047");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(11, "2048-4095");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(12, "4096-8191");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(13, "8192-16383");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");
+
 static struct attribute *spi_dev_attrs[] = {
         &dev_attr_modalias.attr,
         NULL,
@@ -143,6 +165,23 @@ static struct attribute *spi_device_statistics_attrs[] = {
         &dev_attr_spi_device_bytes.attr,
         &dev_attr_spi_device_bytes_rx.attr,
         &dev_attr_spi_device_bytes_tx.attr,
+        &dev_attr_spi_device_transfer_bytes_histo0.attr,
+        &dev_attr_spi_device_transfer_bytes_histo1.attr,
+        &dev_attr_spi_device_transfer_bytes_histo2.attr,
+        &dev_attr_spi_device_transfer_bytes_histo3.attr,
+        &dev_attr_spi_device_transfer_bytes_histo4.attr,
+        &dev_attr_spi_device_transfer_bytes_histo5.attr,
+        &dev_attr_spi_device_transfer_bytes_histo6.attr,
+        &dev_attr_spi_device_transfer_bytes_histo7.attr,
+        &dev_attr_spi_device_transfer_bytes_histo8.attr,
+        &dev_attr_spi_device_transfer_bytes_histo9.attr,
+        &dev_attr_spi_device_transfer_bytes_histo10.attr,
+        &dev_attr_spi_device_transfer_bytes_histo11.attr,
+        &dev_attr_spi_device_transfer_bytes_histo12.attr,
+        &dev_attr_spi_device_transfer_bytes_histo13.attr,
+        &dev_attr_spi_device_transfer_bytes_histo14.attr,
+        &dev_attr_spi_device_transfer_bytes_histo15.attr,
+        &dev_attr_spi_device_transfer_bytes_histo16.attr,
         NULL,
 };
 
@@ -168,6 +207,23 @@ static struct attribute *spi_master_statistics_attrs[] = {
         &dev_attr_spi_master_bytes.attr,
         &dev_attr_spi_master_bytes_rx.attr,
         &dev_attr_spi_master_bytes_tx.attr,
+        &dev_attr_spi_master_transfer_bytes_histo0.attr,
+        &dev_attr_spi_master_transfer_bytes_histo1.attr,
+        &dev_attr_spi_master_transfer_bytes_histo2.attr,
+        &dev_attr_spi_master_transfer_bytes_histo3.attr,
+        &dev_attr_spi_master_transfer_bytes_histo4.attr,
+        &dev_attr_spi_master_transfer_bytes_histo5.attr,
+        &dev_attr_spi_master_transfer_bytes_histo6.attr,
+        &dev_attr_spi_master_transfer_bytes_histo7.attr,
+        &dev_attr_spi_master_transfer_bytes_histo8.attr,
+        &dev_attr_spi_master_transfer_bytes_histo9.attr,
+        &dev_attr_spi_master_transfer_bytes_histo10.attr,
+        &dev_attr_spi_master_transfer_bytes_histo11.attr,
+        &dev_attr_spi_master_transfer_bytes_histo12.attr,
+        &dev_attr_spi_master_transfer_bytes_histo13.attr,
+        &dev_attr_spi_master_transfer_bytes_histo14.attr,
+        &dev_attr_spi_master_transfer_bytes_histo15.attr,
+        &dev_attr_spi_master_transfer_bytes_histo16.attr,
         NULL,
 };
 
@@ -186,10 +242,15 @@ void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
                                        struct spi_master *master)
 {
         unsigned long flags;
+        int l2len = min(fls(xfer->len), SPI_STATISTICS_HISTO_SIZE) - 1;
+
+        if (l2len < 0)
+                l2len = 0;
 
         spin_lock_irqsave(&stats->lock, flags);
 
         stats->transfers++;
+        stats->transfer_bytes_histo[l2len]++;
 
         stats->bytes += xfer->len;
         if ((xfer->tx_buf) &&
@@ -317,6 +378,8 @@ static void spi_drv_shutdown(struct device *dev)
  * spi_register_driver - register a SPI driver
  * @sdrv: the driver to register
  * Context: can sleep
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_register_driver(struct spi_driver *sdrv)
 {
@@ -368,7 +431,7 @@ static DEFINE_MUTEX(board_lock);
  * needs to discard the spi_device without adding it, then it should
  * call spi_dev_put() on it.
  *
- * Returns a pointer to the new device, or NULL.
+ * Return: a pointer to the new device, or NULL.
  */
 struct spi_device *spi_alloc_device(struct spi_master *master)
 {
@@ -427,7 +490,7 @@ static int spi_dev_check(struct device *dev, void *data)
  * Companion function to spi_alloc_device.  Devices allocated with
  * spi_alloc_device can be added onto the spi bus with this function.
  *
- * Returns 0 on success; negative errno on failure
+ * Return: 0 on success; negative errno on failure
  */
 int spi_add_device(struct spi_device *spi)
 {
@@ -500,7 +563,7 @@ EXPORT_SYMBOL_GPL(spi_add_device);
  * this is exported so that for example a USB or parport based adapter
  * driver could add devices (which it would learn about out-of-band).
  *
- * Returns the new device, or NULL.
+ * Return: the new device, or NULL.
  */
 struct spi_device *spi_new_device(struct spi_master *master,
                                   struct spi_board_info *chip)
@@ -572,6 +635,8 @@ static void spi_match_master_to_boardinfo(struct spi_master *master,
  *
  * The board info passed can safely be __initdata ... but be careful of
  * any embedded pointers (platform_data, etc), they're copied as-is.
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 {
@@ -1149,6 +1214,8 @@ static int spi_init_queue(struct spi_master *master)
  *
  * If there are more messages in the queue, the next message is returned from
  * this call.
+ *
+ * Return: the next message in the queue, else NULL if the queue is empty.
  */
 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
 {
@@ -1312,6 +1379,8 @@ static int __spi_queued_transfer(struct spi_device *spi,
  * spi_queued_transfer - transfer function for queued transfers
  * @spi: spi device which is requesting transfer
  * @msg: spi message which is to handled is queued to driver queue
+ *
+ * Return: zero on success, else a negative error code.
  */
 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 {
@@ -1611,12 +1680,13 @@ static struct class spi_master_class = {
  * only ones directly touching chip registers.  It's how they allocate
  * an spi_master structure, prior to calling spi_register_master().
  *
- * This must be called from context that can sleep.  It returns the SPI
- * master structure on success, else NULL.
+ * This must be called from context that can sleep.
  *
  * The caller is responsible for assigning the bus number and initializing
  * the master's methods before calling spi_register_master(); and (after errors
  * adding the device) calling spi_master_put() to prevent a memory leak.
+ *
+ * Return: the SPI master structure on success, else NULL.
  */
 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
 {
@@ -1700,6 +1770,8 @@ static int of_spi_register_master(struct spi_master *master)
  * success, else a negative error code (dropping the master's refcount).
  * After a successful return, the caller is responsible for calling
  * spi_unregister_master().
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_register_master(struct spi_master *master)
 {
@@ -1793,6 +1865,8 @@ static void devm_spi_unregister(struct device *dev, void *res)
  *
  * Register a SPI device as with spi_register_master() which will
  * automatically be unregister
+ *
+ * Return: zero on success, else a negative error code.
  */
 int devm_spi_register_master(struct device *dev, struct spi_master *master)
 {
@@ -1898,6 +1972,8 @@ static int __spi_master_match(struct device *dev, const void *data)
  * arch init time.  It returns a refcounted pointer to the relevant
  * spi_master (which the caller must release), or NULL if there is
  * no such master registered.
+ *
+ * Return: the SPI master structure on success, else NULL.
  */
 struct spi_master *spi_busnum_to_master(u16 bus_num)
 {
@@ -1951,6 +2027,8 @@ static int __spi_validate_bits_per_word(struct spi_master *master, u8 bits_per_w
  * that the underlying controller or its driver does not support.  For
  * example, not all hardware supports wire transfers using nine bit words,
  * LSB-first wire encoding, or active-high chipselects.
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_setup(struct spi_device *spi)
 {
@@ -2169,6 +2247,8 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
  * no other spi_message queued to that device will be processed.
  * (This rule applies equally to all the synchronous transfer calls,
  * which are wrappers around this core asynchronous primitive.)
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_async(struct spi_device *spi, struct spi_message *message)
 {
@@ -2221,6 +2301,8 @@ EXPORT_SYMBOL_GPL(spi_async);
  * no other spi_message queued to that device will be processed.
  * (This rule applies equally to all the synchronous transfer calls,
  * which are wrappers around this core asynchronous primitive.)
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
 {
@@ -2336,7 +2418,7 @@ static int __spi_sync(struct spi_device *spi, struct spi_message *message,
  * Also, the caller is guaranteeing that the memory associated with the
  * message will not be freed before this call returns.
  *
- * It returns zero on success, else a negative error code.
+ * Return: zero on success, else a negative error code.
  */
 int spi_sync(struct spi_device *spi, struct spi_message *message)
 {
@@ -2358,7 +2440,7 @@ EXPORT_SYMBOL_GPL(spi_sync);
  * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
  * be released by a spi_bus_unlock call when the exclusive access is over.
  *
- * It returns zero on success, else a negative error code.
+ * Return: zero on success, else a negative error code.
  */
 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
 {
@@ -2379,7 +2461,7 @@ EXPORT_SYMBOL_GPL(spi_sync_locked);
  * exclusive access is over. Data transfer must be done by spi_sync_locked
  * and spi_async_locked calls when the SPI bus lock is held.
  *
- * It returns zero on success, else a negative error code.
+ * Return: always zero.
  */
 int spi_bus_lock(struct spi_master *master)
 {
@@ -2408,7 +2490,7 @@ EXPORT_SYMBOL_GPL(spi_bus_lock);
  * This call releases an SPI bus lock previously obtained by an spi_bus_lock
  * call.
  *
- * It returns zero on success, else a negative error code.
+ * Return: always zero.
  */
 int spi_bus_unlock(struct spi_master *master)
 {
@@ -2443,6 +2525,8 @@ static u8	*buf;
  * portable code should never use this for more than 32 bytes.
  * Performance-sensitive or bulk transfer code should instead use
  * spi_{async,sync}() calls with dma-safe buffers.
+ *
+ * Return: zero on success, else a negative error code.
  */
 int spi_write_then_read(struct spi_device *spi,
                 const void *txbuf, unsigned n_tx,
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 6b00f18f5e6b..635bff60eda5 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -51,6 +51,8 @@ extern struct bus_type spi_bus_type;
  * @bytes_tx:      number of bytes sent to device
  * @bytes_rx:      number of bytes received from device
  *
+ * @transfer_bytes_histo:
+ *                 transfer bytes histogramm
  */
 struct spi_statistics {
         spinlock_t              lock; /* lock for the whole structure */
@@ -68,6 +70,8 @@ struct spi_statistics {
         unsigned long long      bytes_rx;
         unsigned long long      bytes_tx;
 
+#define SPI_STATISTICS_HISTO_SIZE 17
+        unsigned long transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE];
 };
 
 void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
@@ -843,8 +847,10 @@ extern int spi_bus_unlock(struct spi_master *master);
  * @len: data buffer size
  * Context: can sleep
  *
- * This writes the buffer and returns zero or a negative error code.
+ * This function writes the buffer @buf.
  * Callable only from contexts that can sleep.
+ *
+ * Return: zero on success, else a negative error code.
  */
 static inline int
 spi_write(struct spi_device *spi, const void *buf, size_t len)
@@ -867,8 +873,10 @@ spi_write(struct spi_device *spi, const void *buf, size_t len)
  * @len: data buffer size
  * Context: can sleep
  *
- * This reads the buffer and returns zero or a negative error code.
+ * This function reads the buffer @buf.
  * Callable only from contexts that can sleep.
+ *
+ * Return: zero on success, else a negative error code.
  */
 static inline int
 spi_read(struct spi_device *spi, void *buf, size_t len)
@@ -895,7 +903,7 @@ spi_read(struct spi_device *spi, void *buf, size_t len)
  *
  * For more specific semantics see spi_sync().
  *
- * It returns zero on success, else a negative error code.
+ * Return: Return: zero on success, else a negative error code.
  */
 static inline int
 spi_sync_transfer(struct spi_device *spi, struct spi_transfer *xfers,
@@ -919,9 +927,10 @@ extern int spi_write_then_read(struct spi_device *spi,
  * @cmd: command to be written before data is read back
  * Context: can sleep
  *
- * This returns the (unsigned) eight bit number returned by the
- * device, or else a negative error code.  Callable only from
- * contexts that can sleep.
+ * Callable only from contexts that can sleep.
+ *
+ * Return: the (unsigned) eight bit number returned by the
+ * device, or else a negative error code.
  */
 static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
 {
@@ -940,12 +949,13 @@ static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
  * @cmd: command to be written before data is read back
  * Context: can sleep
  *
- * This returns the (unsigned) sixteen bit number returned by the
- * device, or else a negative error code.  Callable only from
- * contexts that can sleep.
- *
  * The number is returned in wire-order, which is at least sometimes
  * big-endian.
+ *
+ * Callable only from contexts that can sleep.
+ *
+ * Return: the (unsigned) sixteen bit number returned by the
+ * device, or else a negative error code.
  */
 static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
 {
@@ -964,13 +974,13 @@ static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
  * @cmd: command to be written before data is read back
  * Context: can sleep
  *
- * This returns the (unsigned) sixteen bit number returned by the device in cpu
- * endianness, or else a negative error code. Callable only from contexts that
- * can sleep.
- *
  * This function is similar to spi_w8r16, with the exception that it will
  * convert the read 16 bit data word from big-endian to native endianness.
  *
+ * Callable only from contexts that can sleep.
+ *
+ * Return: the (unsigned) sixteen bit number returned by the device in cpu
+ * endianness, or else a negative error code.
  */
 static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd)