From e937cc1dd7966df33a478943817302502a164e25 Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Fri, 6 Mar 2020 16:28:37 +0200 Subject: dmaengine: Add basic debugfs support Via the /sys/kernel/debug/dmaengine/summary users can get information about the DMA devices and the used channels. Example output on am654-evm with audio using two channels and after running dmatest on 4 channels: dma0 (285c0000.dma-controller): number of channels: 96 dma1 (31150000.dma-controller): number of channels: 267 dma1chan0 | 2b00000.mcasp:tx dma1chan1 | 2b00000.mcasp:rx dma1chan2 | in-use dma1chan3 | in-use dma1chan4 | in-use dma1chan5 | in-use For slave channels we can show the device and the channel name a given channel is requested. For non slave devices the only information we know is that the channel is in use. DMA drivers can implement the optional dbg_summary_show callback to provide controller specific information instead of the generic one. It is easy to extend the generic dmaengine_summary_show() to print additional information about the used channels. I have taken the idea from gpiolib and clk subsystems. Signed-off-by: Peter Ujfalusi Link: https://lore.kernel.org/r/20200306142839.17910-2-peter.ujfalusi@ti.com Signed-off-by: Vinod Koul --- drivers/dma/dmaengine.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 75 insertions(+), 1 deletion(-) (limited to 'drivers/dma') diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index c3b1283b6d31..509abc8e8378 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -58,6 +58,65 @@ static DEFINE_IDA(dma_ida); static LIST_HEAD(dma_device_list); static long dmaengine_ref_count; +/* --- debugfs implementation --- */ +#ifdef CONFIG_DEBUG_FS +#include + +static void dmaengine_dbg_summary_show(struct seq_file *s, + struct dma_device *dma_dev) +{ + struct dma_chan *chan; + + list_for_each_entry(chan, &dma_dev->channels, device_node) { + if (chan->client_count) { + seq_printf(s, " %-13s| %s", dma_chan_name(chan), + chan->dbg_client_name ?: "in-use"); + + if (chan->router) + seq_printf(s, " (via router: %s)\n", + dev_name(chan->router->dev)); + else + seq_puts(s, "\n"); + } + } +} + +static int dmaengine_summary_show(struct seq_file *s, void *data) +{ + struct dma_device *dma_dev = NULL; + + mutex_lock(&dma_list_mutex); + list_for_each_entry(dma_dev, &dma_device_list, global_node) { + seq_printf(s, "dma%d (%s): number of channels: %u\n", + dma_dev->dev_id, dev_name(dma_dev->dev), + dma_dev->chancnt); + + if (dma_dev->dbg_summary_show) + dma_dev->dbg_summary_show(s, dma_dev); + else + dmaengine_dbg_summary_show(s, dma_dev); + + if (!list_is_last(&dma_dev->global_node, &dma_device_list)) + seq_puts(s, "\n"); + } + mutex_unlock(&dma_list_mutex); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(dmaengine_summary); + +static void __init dmaengine_debugfs_init(void) +{ + struct dentry *rootdir = debugfs_create_dir("dmaengine", NULL); + + /* /sys/kernel/debug/dmaengine/summary */ + debugfs_create_file("summary", 0444, rootdir, NULL, + &dmaengine_summary_fops); +} +#else +static inline void dmaengine_debugfs_init(void) { } +#endif /* DEBUG_FS */ + /* --- sysfs implementation --- */ #define DMA_SLAVE_NAME "slave" @@ -760,6 +819,11 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name) return chan ? chan : ERR_PTR(-EPROBE_DEFER); found: +#ifdef CONFIG_DEBUG_FS + chan->dbg_client_name = kasprintf(GFP_KERNEL, "%s:%s", dev_name(dev), + name); +#endif + chan->name = kasprintf(GFP_KERNEL, "dma:%s", name); if (!chan->name) return chan; @@ -837,6 +901,11 @@ void dma_release_channel(struct dma_chan *chan) chan->name = NULL; chan->slave = NULL; } + +#ifdef CONFIG_DEBUG_FS + kfree(chan->dbg_client_name); + chan->dbg_client_name = NULL; +#endif mutex_unlock(&dma_list_mutex); } EXPORT_SYMBOL_GPL(dma_release_channel); @@ -1559,6 +1628,11 @@ static int __init dma_bus_init(void) if (err) return err; - return class_register(&dma_devclass); + + err = class_register(&dma_devclass); + if (!err) + dmaengine_debugfs_init(); + + return err; } arch_initcall(dma_bus_init); -- cgit v1.2.3-59-g8ed1b