mfd / platform: cros_ec: Handle chained ECs as platform devices

An MFD is a device that contains several sub-devices (cells). For instance,
the ChromeOS EC fits in this description as usually contains a charger and
can have other devices with different functions like a Real-Time Clock,
an Audio codec, a Real-Time Clock, ...

If you look at the driver, though, we're doing something odd. We have
two MFD cros-ec drivers where one of them (cros-ec-core) instantiates
another MFD driver as sub-driver (cros-ec-dev), and the latest
instantiates the different sub-devices (Real-Time Clock, Audio codec,
etc).

                  MFD
------------------------------------------
   cros-ec-core
       |___ mfd-cellA (cros-ec-dev)
       |       |__ mfd-cell0
       |       |__ mfd-cell1
       |       |__ ...
       |
       |___ mfd-cellB (cros-ec-dev)
               |__ mfd-cell0
               |__ mfd-cell1
               |__ ...

The problem that was trying to solve is to describe some kind of topology for
the case where we have an EC (cros-ec) chained with another EC
(cros-pd). Apart from that this extends the bounds of what MFD was
designed to do we might be interested on have other kinds of topology that
can't be implemented in that way.

Let's prepare the code to move the cros-ec-core part from MFD to
platform/chrome as this is clearly a platform specific thing non-related
to a MFD device.

  platform/chrome  |         MFD
------------------------------------------
                   |
   cros-ec ________|___ cros-ec-dev
                   |       |__ mfd-cell0
                   |       |__ mfd-cell1
                   |       |__ ...
                   |
   cros-pd ________|___ cros-ec-dev
                   |        |__ mfd-cell0
                   |        |__ mfd-cell1
                   |        |__ ...

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 31 insertions, 30 deletions

diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index 2a9ac5213893..a54ad47c7b02 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -13,7 +13,6 @@
 #include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/mfd/core.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/suspend.h>
 #include <asm/unaligned.h>
@@ -31,18 +30,6 @@ static struct cros_ec_platform pd_p = {
 	.cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX),
 };
 
-static const struct mfd_cell ec_cell = {
-	.name = "cros-ec-dev",
-	.platform_data = &ec_p,
-	.pdata_size = sizeof(ec_p),
-};
-
-static const struct mfd_cell ec_pd_cell = {
-	.name = "cros-ec-dev",
-	.platform_data = &pd_p,
-	.pdata_size = sizeof(pd_p),
-};
-
 static irqreturn_t ec_irq_thread(int irq, void *data)
 {
 	struct cros_ec_device *ec_dev = data;
@@ -154,38 +141,42 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 		}
 	}
 
-	err = devm_mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO, &ec_cell,
-				   1, NULL, ec_dev->irq, NULL);
-	if (err) {
-		dev_err(dev,
-			"Failed to register Embedded Controller subdevice %d\n",
-			err);
-		return err;
+	/* Register a platform device for the main EC instance */
+	ec_dev->ec = platform_device_register_data(ec_dev->dev, "cros-ec-dev",
+					PLATFORM_DEVID_AUTO, &ec_p,
+					sizeof(struct cros_ec_platform));
+	if (IS_ERR(ec_dev->ec)) {
+		dev_err(ec_dev->dev,
+			"Failed to create CrOS EC platform device\n");
+		return PTR_ERR(ec_dev->ec);
 	}
 
 	if (ec_dev->max_passthru) {
 		/*
-		 * Register a PD device as well on top of this device.
+		 * Register a platform device for the PD behind the main EC.
 		 * We make the following assumptions:
 		 * - behind an EC, we have a pd
 		 * - only one device added.
 		 * - the EC is responsive at init time (it is not true for a
-		 *   sensor hub.
+		 *   sensor hub).
 		 */
-		err = devm_mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO,
-				      &ec_pd_cell, 1, NULL, ec_dev->irq, NULL);
-		if (err) {
-			dev_err(dev,
-				"Failed to register Power Delivery subdevice %d\n",
-				err);
-			return err;
+		ec_dev->pd = platform_device_register_data(ec_dev->dev,
+					"cros-ec-dev",
+					PLATFORM_DEVID_AUTO, &pd_p,
+					sizeof(struct cros_ec_platform));
+		if (IS_ERR(ec_dev->pd)) {
+			dev_err(ec_dev->dev,
+				"Failed to create CrOS PD platform device\n");
+			platform_device_unregister(ec_dev->ec);
+			return PTR_ERR(ec_dev->pd);
 		}
 	}
 
 	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
 		err = devm_of_platform_populate(dev);
 		if (err) {
-			mfd_remove_devices(dev);
+			platform_device_unregister(ec_dev->pd);
+			platform_device_unregister(ec_dev->ec);
 			dev_err(dev, "Failed to register sub-devices\n");
 			return err;
 		}
@@ -206,6 +197,16 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 }
 EXPORT_SYMBOL(cros_ec_register);
 
+int cros_ec_unregister(struct cros_ec_device *ec_dev)
+{
+	if (ec_dev->pd)
+		platform_device_unregister(ec_dev->pd);
+	platform_device_unregister(ec_dev->ec);
+
+	return 0;
+}
+EXPORT_SYMBOL(cros_ec_unregister);
+
 #ifdef CONFIG_PM_SLEEP
 int cros_ec_suspend(struct cros_ec_device *ec_dev)
 {