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authorMartin Sperl <kernel@martin.sperl.org>2019-04-23 23:15:13 +0300
committerMark Brown <broonie@kernel.org>2019-05-08 11:59:47 +0300
commit154f7da56f1ecba42021d550c9e8432ac8d32c26 (patch)
tree184739c135821c9e1456a4a7797e903c8ca44b57 /drivers/spi/spi-bcm2835.c
parentff245d90ebed8d4da6751dfee1bc76e4a5e94257 (diff)
downloadlinux-154f7da56f1ecba42021d550c9e8432ac8d32c26.tar.xz
spi: bcm2835: add driver stats to debugfs
To estimate efficiency add statistics on transfer types (polling, interrupt and dma) used to debugfs. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions fixed compile issue when CONFIG_DEBUG_FS is unset Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spi-bcm2835.c')
-rw-r--r--drivers/spi/spi-bcm2835.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 3230d37fa89a..eb67da697ef5 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -22,6 +22,7 @@
#include <linux/clk.h>
#include <linux/completion.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
@@ -101,6 +102,15 @@ MODULE_PARM_DESC(polling_limit_us,
* length is not a multiple of 4 (to overcome hardware limitation)
* @tx_spillover: whether @tx_prologue spills over to second TX sglist entry
* @dma_pending: whether a DMA transfer is in progress
+ * @debugfs_dir: the debugfs directory - neede to remove debugfs when
+ * unloading the module
+ * @count_transfer_polling: count of how often polling mode is used
+ * @count_transfer_irq: count of how often interrupt mode is used
+ * @count_transfer_irq_after_polling: count of how often we fall back to
+ * interrupt mode after starting in polling mode.
+ * These are counted as well in @count_transfer_polling and
+ * @count_transfer_irq
+ * @count_transfer_dma: count how often dma mode is used
*/
struct bcm2835_spi {
void __iomem *regs;
@@ -115,8 +125,55 @@ struct bcm2835_spi {
int rx_prologue;
unsigned int tx_spillover;
unsigned int dma_pending;
+
+ struct dentry *debugfs_dir;
+ u64 count_transfer_polling;
+ u64 count_transfer_irq;
+ u64 count_transfer_irq_after_polling;
+ u64 count_transfer_dma;
};
+#if defined(CONFIG_DEBUG_FS)
+static void bcm2835_debugfs_create(struct bcm2835_spi *bs,
+ const char *dname)
+{
+ char name[64];
+ struct dentry *dir;
+
+ /* get full name */
+ snprintf(name, sizeof(name), "spi-bcm2835-%s", dname);
+
+ /* the base directory */
+ dir = debugfs_create_dir(name, NULL);
+ bs->debugfs_dir = dir;
+
+ /* the counters */
+ debugfs_create_u64("count_transfer_polling", 0444, dir,
+ &bs->count_transfer_polling);
+ debugfs_create_u64("count_transfer_irq", 0444, dir,
+ &bs->count_transfer_irq);
+ debugfs_create_u64("count_transfer_irq_after_polling", 0444, dir,
+ &bs->count_transfer_irq_after_polling);
+ debugfs_create_u64("count_transfer_dma", 0444, dir,
+ &bs->count_transfer_dma);
+}
+
+static void bcm2835_debugfs_remove(struct bcm2835_spi *bs)
+{
+ debugfs_remove_recursive(bs->debugfs_dir);
+ bs->debugfs_dir = NULL;
+}
+#else
+static void bcm2835_debugfs_create(struct bcm2835_spi *bs,
+ const char *dname)
+{
+}
+
+static void bcm2835_debugfs_remove(struct bcm2835_spi *bs)
+{
+}
+#endif /* CONFIG_DEBUG_FS */
+
static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg)
{
return readl(bs->regs + reg);
@@ -320,6 +377,9 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
+ /* update usage statistics */
+ bs->count_transfer_irq++;
+
/*
* Enable HW block, but with interrupts still disabled.
* Otherwise the empty TX FIFO would immediately trigger an interrupt.
@@ -564,6 +624,9 @@ static int bcm2835_spi_transfer_one_dma(struct spi_master *master,
struct bcm2835_spi *bs = spi_master_get_devdata(master);
int ret;
+ /* update usage statistics */
+ bs->count_transfer_dma++;
+
/*
* Transfer first few bytes without DMA if length of first TX or RX
* sglist entry is not a multiple of 4 bytes (hardware limitation).
@@ -706,6 +769,9 @@ static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
struct bcm2835_spi *bs = spi_master_get_devdata(master);
unsigned long timeout;
+ /* update usage statistics */
+ bs->count_transfer_polling++;
+
/* enable HW block without interrupts */
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
@@ -735,6 +801,10 @@ static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
jiffies - timeout,
bs->tx_len, bs->rx_len);
/* fall back to interrupt mode */
+
+ /* update usage statistics */
+ bs->count_transfer_irq_after_polling++;
+
return bcm2835_spi_transfer_one_irq(master, spi,
tfr, cs, false);
}
@@ -982,6 +1052,8 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
goto out_clk_disable;
}
+ bcm2835_debugfs_create(bs, dev_name(&pdev->dev));
+
return 0;
out_clk_disable:
@@ -996,6 +1068,8 @@ static int bcm2835_spi_remove(struct platform_device *pdev)
struct spi_master *master = platform_get_drvdata(pdev);
struct bcm2835_spi *bs = spi_master_get_devdata(master);
+ bcm2835_debugfs_remove(bs);
+
/* Clear FIFOs, and disable the HW block */
bcm2835_wr(bs, BCM2835_SPI_CS,
BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);