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Unverified Commit 154f7da5 authored by Martin Sperl's avatar Martin Sperl Committed by Mark Brown
Browse files

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: default avatarMartin 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: default avatarMark Brown <broonie@kernel.org>
parent ff245d90

drivers/spi/spi-bcm2835.c

+74 −0
Original line number Diff line number Diff line
@@ -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);