This commit implements the runtime PM operations to disable eMMC
card clock when idle.

Reviewed-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Liming Sun <limings@nvidia.com>
---
v2->v3:
    - Revise the commit message;
v1->v2:
    Updates for comments from Ulf:
    - Make the runtime PM logic generic for sdhci-of-dwcmshc;
v1: Initial version.
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 56 ++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index e68cd87998c8..a3277f4d250d 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/reset.h>
 #include <linux/sizes.h>
 
@@ -546,6 +547,8 @@ static int dwcmshc_probe(struct platform_device *pdev)
 		sdhci_enable_v4_mode(host);
 #endif
 
+	pm_runtime_enable(dev);
+
 	host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
 
 	err = sdhci_setup_host(host);
@@ -646,7 +649,58 @@ static int dwcmshc_resume(struct device *dev)
 }
 #endif
 
-static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
+#ifdef CONFIG_PM
+
+#ifdef CONFIG_ACPI
+static void dwcmshc_enable_card_clk(struct sdhci_host *host)
+{
+	u16 ctrl;
+
+	ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+	ctrl |= SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
+}
+
+static void dwcmshc_disable_card_clk(struct sdhci_host *host)
+{
+	u16 ctrl;
+
+	ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+	ctrl &= ~SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
+}
+#endif
+
+static int dwcmshc_runtime_suspend(struct device *dev)
+{
+	struct sdhci_host *host = dev_get_drvdata(dev);
+	int ret = 0;
+
+	ret = sdhci_runtime_suspend_host(host);
+	if (!ret)
+		dwcmshc_disable_card_clk(host);
+
+	return ret;
+}
+
+static int dwcmshc_runtime_resume(struct device *dev)
+{
+	struct sdhci_host *host = dev_get_drvdata(dev);
+	int ret = 0;
+
+	dwcmshc_enable_card_clk(host);
+	ret = sdhci_runtime_resume_host(host, 0);
+
+	return ret;
+}
+
+#endif
+
+static const struct dev_pm_ops dwcmshc_pmops = {
+	SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend, dwcmshc_resume)
+	SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
+			   dwcmshc_runtime_resume, NULL)
+};
 
 static struct platform_driver sdhci_dwcmshc_driver = {
 	.driver	= {
-- 
2.30.1

Hi Liming,

kernel test robot noticed the following build errors:

[auto build test ERROR on ulf-hansson-mmc-mirror/next]
[also build test ERROR on linus/master v6.4-rc1 next-20230512]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Liming-Sun/mmc-sdhci-of-dwcmshc-Add-runtime-PM-operations/20230512-202948
base:   https://git.linaro.org/people/ulf.hansson/mmc-mirror.git next
patch link:    https://lore.kernel.org/r/20230512122648.223974-1-limings%40nvidia.com
patch subject: [PATCH v3] mmc: sdhci-of-dwcmshc: Add runtime PM operations
config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20230513/202305130116.ynGq0pC5-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/eb5d4c0702ce24630f3d82a37f39437f52607cbb
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Liming-Sun/mmc-sdhci-of-dwcmshc-Add-runtime-PM-operations/20230512-202948
        git checkout eb5d4c0702ce24630f3d82a37f39437f52607cbb
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202305130116.ynGq0pC5-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/mmc/host/sdhci-of-dwcmshc.c: In function 'dwcmshc_runtime_suspend':
>> drivers/mmc/host/sdhci-of-dwcmshc.c:674:17: error: implicit declaration of function 'dwcmshc_disable_card_clk' [-Werror=implicit-function-declaration]
     674 |                 dwcmshc_disable_card_clk(host);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~
   drivers/mmc/host/sdhci-of-dwcmshc.c: In function 'dwcmshc_runtime_resume':
>> drivers/mmc/host/sdhci-of-dwcmshc.c:684:9: error: implicit declaration of function 'dwcmshc_enable_card_clk' [-Werror=implicit-function-declaration]
     684 |         dwcmshc_enable_card_clk(host);
         |         ^~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/dwcmshc_disable_card_clk +674 drivers/mmc/host/sdhci-of-dwcmshc.c

   666	
   667	static int dwcmshc_runtime_suspend(struct device *dev)
   668	{
   669		struct sdhci_host *host = dev_get_drvdata(dev);
   670		int ret = 0;
   671	
   672		ret = sdhci_runtime_suspend_host(host);
   673		if (!ret)
 > 674			dwcmshc_disable_card_clk(host);
   675	
   676		return ret;
   677	}
   678	
   679	static int dwcmshc_runtime_resume(struct device *dev)
   680	{
   681		struct sdhci_host *host = dev_get_drvdata(dev);
   682		int ret = 0;
   683	
 > 684		dwcmshc_enable_card_clk(host);
   685		ret = sdhci_runtime_resume_host(host, 0);
   686	
   687		return ret;
   688	}
   689	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests