diff options
| author | Sujit Reddy Thumma <sthumma@codeaurora.org> | 2012-11-09 18:32:32 +0530 |
|---|---|---|
| committer | Subhash Jadavani <subhashj@codeaurora.org> | 2016-05-27 10:29:15 -0700 |
| commit | 7d7218224b477ffb208655be43996fdfdb9d8370 (patch) | |
| tree | 9cc0618db545d66da7e91bd0cc5148c75fd0a535 /drivers | |
| parent | f3bca6c7763f02d8f1318aa840e4a3780ab219f2 (diff) | |
mmc: core: Add a debugfs entry to set max clock rate
Limiting the max frequency supported by host controller
to a certain value can be useful for testing power consumption
at various frequencies that are supported by the host.
Note: If the card supports less than desired value then the
frequency of operation would be limited to that frequency.
Usage:
mount -t debugfs none /sys/kernel/debug
echo <desired_frequency> > /sys/kernel/debug/mmcX/max_clock
cat /sys/kernel/debug/mmcX/max_clock
Change-Id: I9e9a7e368f56d8e16548780288211bd8775fd048
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mmc/core/debugfs.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c index f4db93e03e88..cbc83344e0c7 100644 --- a/drivers/mmc/core/debugfs.c +++ b/drivers/mmc/core/debugfs.c @@ -233,6 +233,46 @@ static int mmc_clock_opt_set(void *data, u64 val) DEFINE_SIMPLE_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set, "%llu\n"); +static int mmc_max_clock_get(void *data, u64 *val) +{ + struct mmc_host *host = data; + + if (!host) + return -EINVAL; + + *val = host->f_max; + + return 0; +} + +static int mmc_max_clock_set(void *data, u64 val) +{ + struct mmc_host *host = data; + int err = -EINVAL; + unsigned long freq = val; + unsigned int old_freq; + + if (!host || (val < host->f_min)) + goto out; + + mmc_claim_host(host); + if (host->bus_ops && host->bus_ops->change_bus_speed) { + old_freq = host->f_max; + host->f_max = freq; + + err = host->bus_ops->change_bus_speed(host, &freq); + + if (err) + host->f_max = old_freq; + } + mmc_release_host(host); +out: + return err; +} + +DEFINE_SIMPLE_ATTRIBUTE(mmc_max_clock_fops, mmc_max_clock_get, + mmc_max_clock_set, "%llu\n"); + void mmc_add_host_debugfs(struct mmc_host *host) { struct dentry *root; @@ -255,6 +295,10 @@ void mmc_add_host_debugfs(struct mmc_host *host) &mmc_clock_fops)) goto err_node; + if (!debugfs_create_file("max_clock", S_IRUSR | S_IWUSR, root, host, + &mmc_max_clock_fops)) + goto err_node; + #ifdef CONFIG_MMC_CLKGATE if (!debugfs_create_u32("clk_delay", (S_IRUSR | S_IWUSR), root, &host->clk_delay)) |