Messages in this thread Patch in this message | | | From | Andy Shevchenko <> | Subject | [PATCH] mmc: append a file to change host clock at run time | Date | Tue, 12 Oct 2010 18:17:22 +0300 |
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For debugging power managment features there is quite convenient to have a possibility to change MMC host controller clock at run time. This patch adds 'clock' file under MMC host root of debugfs.
Usage as follows:
# cat /sys/kernel/debug/mmc0/clock 24000000
# echo "1000000000" > /sys/kernel/debug/mmc0/clock # cat /sys/kernel/debug/mmc0/clock 52000000
# echo "48000000" > /sys/kernel/debug/mmc0/clock # cat /sys/kernel/debug/mmc0/clock 48000000
The second piece of example shows limits which are applied accordingly to used host driver.
Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com> --- drivers/mmc/core/debugfs.c | 33 +++++++++++++++++++++++++++++++-- 1 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c index 96d10f4..4ff109f 100644 --- a/drivers/mmc/core/debugfs.c +++ b/drivers/mmc/core/debugfs.c @@ -133,6 +133,31 @@ static const struct file_operations mmc_ios_fops = { .release = single_release, }; +static int mmc_clock_opt_get(void *data, u64 *val) +{ + struct mmc_host *host = data; + + *val = host->ios.clock; + + return 0; +} + +static int mmc_clock_opt_set(void *data, u64 val) +{ + struct mmc_host *host = data; + + /* We need this check due to input value is u64 */ + if (val > host->f_max) + return -EINVAL; + + mmc_set_clock(host, (unsigned int) val); + + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set, + "%llu\n"); + void mmc_add_host_debugfs(struct mmc_host *host) { struct dentry *root; @@ -149,11 +174,15 @@ void mmc_add_host_debugfs(struct mmc_host *host) host->debugfs_root = root; if (!debugfs_create_file("ios", S_IRUSR, root, host, &mmc_ios_fops)) - goto err_ios; + goto err_node; + + if (!debugfs_create_file("clock", S_IRUSR | S_IWUSR, root, host, + &mmc_clock_fops)) + goto err_node; return; -err_ios: +err_node: debugfs_remove_recursive(root); host->debugfs_root = NULL; err_root: -- 1.6.3.3
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