soc: samsung: exynos-chipid: convert to driver and merge exynos-asv

The Exynos Chip ID driver on Exynos SoCs has so far only informational
purpose - to expose the SoC device in sysfs.  No other drivers depend on
it so there is really no benefit of initializing it early.

The code would be the most flexible if converted to a regular driver.
However there is already another driver - Exynos ASV (Adaptive Supply
Voltage) - which binds to the device node of Chip ID.

The solution is to convert the Exynos Chip ID to a built in driver and
merge the Exynos ASV into it.

This has several benefits:
1. Although the Exynos ASV driver binds to a device node present in all
   Exynos DTS (generic compatible), it fails to probe except on the
   supported ones (only Exynos5422).  This means that the regular boot
   process has a planned/normal device probe failure.

   Merging the ASV into Chip ID will remove this probe failure because
   the final driver will always bind, just with disabled ASV features.

2. Allows to use dev_info() as the SoC bus is present (since
   core_initcall).

3. Could speed things up because of execution of Chip ID code in a SMP
   environment (after bringing up secondary CPUs, unlike early_initcall),
   This reduces the amount of work to be done early, when the kernel has
   to bring up critical devices.

5. Makes the Chip ID code defer-probe friendly,

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201207190517.262051-5-krzk@kernel.org
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>

1 files changed, 11 insertions, 34 deletions

diff --git a/drivers/soc/samsung/exynos-asv.c b/drivers/soc/samsung/exynos-asv.c
index 5daeadc36382..d60af8acc391 100644
--- a/drivers/soc/samsung/exynos-asv.c
+++ b/drivers/soc/samsung/exynos-asv.c
@@ -2,7 +2,9 @@
 /*
  * Copyright (c) 2019 Samsung Electronics Co., Ltd.
  *	      http://www.samsung.com/
+ * Copyright (c) 2020 Krzysztof Kozlowski <krzk@kernel.org>
  * Author: Sylwester Nawrocki <s.nawrocki@samsung.com>
+ * Author: Krzysztof Kozlowski <krzk@kernel.org>
  *
  * Samsung Exynos SoC Adaptive Supply Voltage support
  */
@@ -10,12 +12,7 @@
 #include <linux/cpu.h>
 #include <linux/device.h>
 #include <linux/errno.h>
-#include <linux/init.h>
-#include <linux/mfd/syscon.h>
-#include <linux/module.h>
 #include <linux/of.h>
-#include <linux/of_device.h>
-#include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/regmap.h>
 #include <linux/soc/samsung/exynos-chipid.h>
@@ -111,7 +108,7 @@ static int exynos_asv_update_opps(struct exynos_asv *asv)
 	return	0;
 }
 
-static int exynos_asv_probe(struct platform_device *pdev)
+int exynos_asv_init(struct device *dev, struct regmap *regmap)
 {
 	int (*probe_func)(struct exynos_asv *asv);
 	struct exynos_asv *asv;
@@ -119,21 +116,16 @@ static int exynos_asv_probe(struct platform_device *pdev)
 	u32 product_id = 0;
 	int ret, i;
 
-	asv = devm_kzalloc(&pdev->dev, sizeof(*asv), GFP_KERNEL);
+	asv = devm_kzalloc(dev, sizeof(*asv), GFP_KERNEL);
 	if (!asv)
 		return -ENOMEM;
 
-	asv->chipid_regmap = device_node_to_regmap(pdev->dev.of_node);
-	if (IS_ERR(asv->chipid_regmap)) {
-		dev_err(&pdev->dev, "Could not find syscon regmap\n");
-		return PTR_ERR(asv->chipid_regmap);
-	}
-
+	asv->chipid_regmap = regmap;
+	asv->dev = dev;
 	ret = regmap_read(asv->chipid_regmap, EXYNOS_CHIPID_REG_PRO_ID,
 			  &product_id);
 	if (ret < 0) {
-		dev_err(&pdev->dev, "Cannot read revision from ChipID: %d\n",
-			ret);
+		dev_err(dev, "Cannot read revision from ChipID: %d\n", ret);
 		return -ENODEV;
 	}
 
@@ -142,7 +134,9 @@ static int exynos_asv_probe(struct platform_device *pdev)
 		probe_func = exynos5422_asv_init;
 		break;
 	default:
-		return -ENODEV;
+		dev_dbg(dev, "No ASV support for this SoC\n");
+		devm_kfree(dev, asv);
+		return 0;
 	}
 
 	cpu_dev = get_cpu_device(0);
@@ -150,14 +144,11 @@ static int exynos_asv_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return -EPROBE_DEFER;
 
-	ret = of_property_read_u32(pdev->dev.of_node, "samsung,asv-bin",
+	ret = of_property_read_u32(dev->of_node, "samsung,asv-bin",
 				   &asv->of_bin);
 	if (ret < 0)
 		asv->of_bin = -EINVAL;
 
-	asv->dev = &pdev->dev;
-	dev_set_drvdata(&pdev->dev, asv);
-
 	for (i = 0; i < ARRAY_SIZE(asv->subsys); i++)
 		asv->subsys[i].asv = asv;
 
@@ -167,17 +158,3 @@ static int exynos_asv_probe(struct platform_device *pdev)
 
 	return exynos_asv_update_opps(asv);
 }
-
-static const struct of_device_id exynos_asv_of_device_ids[] = {
-	{ .compatible = "samsung,exynos4210-chipid" },
-	{}
-};
-
-static struct platform_driver exynos_asv_driver = {
-	.driver = {
-		.name = "exynos-asv",
-		.of_match_table = exynos_asv_of_device_ids,
-	},
-	.probe	= exynos_asv_probe,
-};
-module_platform_driver(exynos_asv_driver);