spi: bcm2835aux: add driver stats to debugfs

To estimate efficiency add statistics on transfer types
(polling and interrupt) used to debugfs.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm2835aux.c

@@ -21,6 +21,7 @@
 
 #include <linux/clk.h>
 #include <linux/completion.h>
+#include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
@@ -104,8 +105,52 @@ struct bcm2835aux_spi {
 	int tx_len;
 	int rx_len;
 	int pending;
+
+	u64 count_transfer_polling;
+	u64 count_transfer_irq;
+	u64 count_transfer_irq_after_poll;
+
+	struct dentry *debugfs_dir;
 };
 
+#if defined(CONFIG_DEBUG_FS)
+static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs,
+				      const char *dname)
+{
+	char name[64];
+	struct dentry *dir;
+
+	/* get full name */
+	snprintf(name, sizeof(name), "spi-bcm2835aux-%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_poll", 0444, dir,
+			   &bs->count_transfer_irq_after_poll);
+}
+
+static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
+{
+	debugfs_remove_recursive(bs->debugfs_dir);
+	bs->debugfs_dir = NULL;
+}
+#else
+static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs)
+{
+}
+
+static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
+{
+}
+#endif /* CONFIG_DEBUG_FS */
+
 static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg)
 {
 	return readl(bs->regs + reg);
@@ -244,6 +289,9 @@ static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
 {
 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
 
+	/* update statistics */
+	bs->count_transfer_irq++;
+
 	/* fill in registers and fifos before enabling interrupts */
 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
@@ -267,6 +315,9 @@ static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
 	unsigned long timeout;
 
+	/* update statistics */
+	bs->count_transfer_polling++;
+
 	/* configure spi */
 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
@@ -287,6 +338,7 @@ static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
 					    jiffies - timeout,
 					    bs->tx_len, bs->rx_len);
 			/* forward to interrupt handler */
+			bs->count_transfer_irq_after_poll++;
 			return __bcm2835aux_spi_transfer_one_irq(master,
 							       spi, tfr);
 		}
@@ -536,6 +588,8 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
 		goto out_clk_disable;
 	}
 
+	bcm2835aux_debugfs_create(bs, dev_name(&pdev->dev));
+
 	return 0;
 
 out_clk_disable:
@@ -550,6 +604,8 @@ static int bcm2835aux_spi_remove(struct platform_device *pdev)
 	struct spi_master *master = platform_get_drvdata(pdev);
 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
 
+	bcm2835aux_debugfs_remove(bs);
+
 	bcm2835aux_spi_reset_hw(bs);
 
 	/* disable the HW block by releasing the clock */