From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sayali Lokhande Subject: [PATCH RFC 7/7] mmc: core: Add a debugfs entry to set max clock rate Date: Fri, 13 Jul 2018 15:23:03 +0530 Message-ID: <1531475583-7050-8-git-send-email-sayalil@codeaurora.org> References: <1531475583-7050-1-git-send-email-sayalil@codeaurora.org> Return-path: In-Reply-To: <1531475583-7050-1-git-send-email-sayalil@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: adrian.hunter@intel.com, ulf.hansson@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, shawn.lin@rock-chips.com, linux-arm-msm@vger.kernel.org, georgi.djakov@linaro.org, devicetree@vger.kernel.org, asutoshd@codeaurora.org, stummala@codeaurora.org, venkatg@codeaurora.org, vviswana@codeaurora.org, bjorn.andersson@linaro.org, riteshh@codeaurora.org, vbadigan@codeaurora.org, sayalil@codeaurora.org, Sujit Reddy Thumma List-Id: devicetree@vger.kernel.org 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 > /sys/kernel/debug/mmcX/max_clock cat /sys/kernel/debug/mmcX/max_clock Signed-off-by: Sujit Reddy Thumma Signed-off-by: Sayali Lokhande --- drivers/mmc/core/debugfs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c index 630ca8e..26499f7 100644 --- a/drivers/mmc/core/debugfs.c +++ b/drivers/mmc/core/debugfs.c @@ -262,6 +262,46 @@ static int mmc_scale_set(void *data, u64 val) DEFINE_SIMPLE_ATTRIBUTE(mmc_scale_fops, mmc_scale_get, mmc_scale_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; @@ -290,6 +330,10 @@ void mmc_add_host_debugfs(struct mmc_host *host) &mmc_clock_fops)) goto err_node; + if (!debugfs_create_file("max_clock", 0600, root, host, + &mmc_max_clock_fops)) + goto err_node; + if (!debugfs_create_file("scale", 0600, root, host, &mmc_scale_fops)) goto err_node; -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project