[PATCH v21 05/13] mfd: psci-mfd: Add PSCI MFD driver for cpuidle-psci-domain cell

[Shivendra Pratap]

PSCI has multiple kernel consumers, such as cpuidle-psci-domain.
Currently, both the PSCI core driver and cpuidle-psci-domain bind
directly to the same PSCI node "arm,psci-1.0". Additional consumers, if
introduced, would also need to bind in the same way, leading to several
drivers attached to a single device node.

Introduce a PSCI MFD driver that binds to "arm,psci-1.0" and registers
PSCI child cells. As the first user, register cpuidle-psci-domain as a
child cell.

Update cpuidle-psci-domain to probe as an MFD child and use the parent
PSCI node for power-domain traversal.

Signed-off-by: Shivendra Pratap <shivendra.pratap at oss.qualcomm.com>
---
 MAINTAINERS                           |  1 +
 drivers/cpuidle/Kconfig.arm           |  1 +
 drivers/cpuidle/cpuidle-psci-domain.c |  9 +-------
 drivers/mfd/Kconfig                   | 10 ++++++++
 drivers/mfd/Makefile                  |  2 ++
 drivers/mfd/psci-mfd.c                | 43 +++++++++++++++++++++++++++++++++++
 6 files changed, 58 insertions(+), 8 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index c871acf2179ce16c80b404027e6b969c7787a6bb..333b01fa00b8fbd15e6f31a6b9af47600411624e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21239,6 +21239,7 @@ L:	linux-arm-kernel at lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	Documentation/devicetree/bindings/arm/psci.yaml
 F:	drivers/firmware/psci/
+F:	drivers/mfd/psci-mfd.c
 F:	include/linux/psci.h
 F:	include/uapi/linux/psci.h
 
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index a1ee475d180dacab245510674514811aec337ad3..1a1316d11e0a2e4f61801586229f5104e2435865 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -36,6 +36,7 @@ config ARM_PSCI_CPUIDLE_DOMAIN
 	bool "PSCI CPU idle Domain"
 	depends on ARM_PSCI_CPUIDLE
 	depends on PM_GENERIC_DOMAINS_OF
+	depends on MFD_PSCI
 	select DT_IDLE_GENPD
 	default y
 	help
diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index b9e4ad7d43a3310a76ce62018dff0af1488e33d2..a2d01810f2957abdfa52ae66503dc0cbb205f163 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -17,7 +17,6 @@
 #include <linux/pm_runtime.h>
 #include <linux/psci.h>
 #include <linux/slab.h>
-#include <linux/string.h>
 
 #include "cpuidle-psci.h"
 #include "dt_idle_genpd.h"
@@ -122,14 +121,9 @@ static void psci_pd_remove(void)
 	}
 }
 
-static const struct of_device_id psci_of_match[] = {
-	{ .compatible = "arm,psci-1.0" },
-	{}
-};
-
 static int psci_cpuidle_domain_probe(struct platform_device *pdev)
 {
-	struct device_node *np = pdev->dev.of_node;
+	struct device_node *np = pdev->dev.parent->of_node;
 	bool use_osi = psci_has_osi_support();
 	int ret = 0, pd_count = 0;
 
@@ -181,7 +175,6 @@ static struct platform_driver psci_cpuidle_domain_driver = {
 	.probe  = psci_cpuidle_domain_probe,
 	.driver = {
 		.name = "psci-cpuidle-domain",
-		.of_match_table = psci_of_match,
 	},
 };
 
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 7192c9d1d268e93d1557ca6519ac96056e37e221..75ea5b47315cedfd1153899eef28614a165a14f5 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2376,6 +2376,16 @@ config MFD_KHADAS_MCU
 	  additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_PSCI
+	bool "PSCI MFD for psci child cells"
+	depends on ARM_PSCI_FW
+	select MFD_CORE
+	help
+	  PSCI MFD registers PSCI child cells and exposes them as
+	  platform devices. Child drivers are probed only if enabled in the
+	  kernel configuration. Select this option whenever a supported PSCI
+	  child driver is selected.
+
 config MFD_ACER_A500_EC
 	tristate "Support for Acer Iconia Tab A500 Embedded Controller"
 	depends on I2C
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index e75e8045c28afae975ac61d282b3b85af5440119..36e872b11b995135a04ca24c33fd3a4d08e4f49a 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -24,6 +24,8 @@ obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
 obj-$(CONFIG_MFD_GATEWORKS_GSC)	+= gateworks-gsc.o
 obj-$(CONFIG_MFD_MACSMC)	+= macsmc.o
 
+obj-$(CONFIG_MFD_PSCI)		+= psci-mfd.o
+
 obj-$(CONFIG_MFD_TI_LP873X)	+= lp873x.o
 obj-$(CONFIG_MFD_TI_LP87565)	+= lp87565.o
 obj-$(CONFIG_MFD_TI_AM335X_TSCADC)	+= ti_am335x_tscadc.o
diff --git a/drivers/mfd/psci-mfd.c b/drivers/mfd/psci-mfd.c
new file mode 100644
index 0000000000000000000000000000000000000000..7affd6bb09dd83452664edeccb09290fe4f43186
--- /dev/null
+++ b/drivers/mfd/psci-mfd.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static const struct mfd_cell psci_cells[] = {
+	{
+		.name = "psci-cpuidle-domain",
+	},
+};
+
+static int psci_mfd_probe(struct platform_device *pdev)
+{
+	return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, psci_cells,
+				   ARRAY_SIZE(psci_cells), NULL, 0, NULL);
+}
+
+static const struct of_device_id psci_mfd_of_match[] = {
+	{ .compatible = "arm,psci-1.0" },
+	{ }
+};
+
+static struct platform_driver psci_mfd_driver = {
+	.probe = psci_mfd_probe,
+	.driver = {
+		.name = "psci-mfd",
+		.of_match_table = psci_mfd_of_match,
+	},
+};
+
+static int __init psci_mfd_init(void)
+{
+	return platform_driver_register(&psci_mfd_driver);
+}
+
+core_initcall(psci_mfd_init);
+
+MODULE_LICENSE("GPL");

-- 
2.34.1