[PATCH v4 3/4] soc: ti: k3-socinfo: Export SoC registration helper

[Moteen Shah]

The k3-socinfo driver reads the JTAG ID through a dedicated MMIO region and
then decodes it and registers the SoC device.

Newer TI SoCs like TDA54 use a different path for accessing the JTAG ID
register, but the decoding of the JTAG ID into the SoC information remains
the same.

Split the decode and registration part out of k3_chipinfo_probe() into
k3_socinfo_register() and export it, so that other drivers can register the
SoC device once they have read the JTAG ID through their own access path.
The registration is managed by the calling device, so callers need no
unregister counterpart.

Signed-off-by: Moteen Shah <m-shah@xxxxxx>
---
Changes since v3:
- Add the missing k3-socinfo public header declaring k3_socinfo_register().

Changes since v2:
- Split out the devm related changes into a new patch (see PATCH 2/4).

 drivers/soc/ti/k3-socinfo.c       | 70 ++++++++++++++++++++-----------
 include/linux/soc/ti/k3-socinfo.h | 11 +++++
 2 files changed, 57 insertions(+), 24 deletions(-)
 create mode 100644 include/linux/soc/ti/k3-socinfo.h

diff --git a/drivers/soc/ti/k3-socinfo.c b/drivers/soc/ti/k3-socinfo.c
index e21a2cd14c811..bf0829fb1d61c 100644
--- a/drivers/soc/ti/k3-socinfo.c
+++ b/drivers/soc/ti/k3-socinfo.c
@@ -5,6 +5,8 @@
  * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com
  */
 
+#include <linux/device.h>
+#include <linux/export.h>
 #include <linux/mfd/syscon.h>
 #include <linux/nvmem-consumer.h>
 #include <linux/of.h>
@@ -12,6 +14,7 @@
 #include <linux/regmap.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/soc/ti/k3-socinfo.h>
 #include <linux/string.h>
 #include <linux/sys_soc.h>
 
@@ -152,43 +155,32 @@ k3_chipinfo_variant_to_sr(struct device *dev, unsigned int partno,
 	return -ENODEV;
 }
 
-static const struct regmap_config k3_chipinfo_regmap_cfg = {
-	.reg_bits = 32,
-	.val_bits = 32,
-	.reg_stride = 4,
-};
-
 static void k3_chipinfo_unregister(void *data)
 {
 	soc_device_unregister(data);
 }
 
-static int k3_chipinfo_probe(struct platform_device *pdev)
+/**
+ * k3_socinfo_register() - Decode a JTAG ID and register the SoC device
+ * @dev: device on whose behalf the SoC device is registered
+ * @jtag_id: raw JTAG ID register value read by the caller
+ *
+ * The registration is managed by @dev: the SoC device is unregistered and its
+ * attributes are released automatically when @dev is unbound, so callers need
+ * no matching unregister call.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int k3_socinfo_register(struct device *dev, u32 jtag_id)
 {
-	struct device_node *node = pdev->dev.of_node;
+	struct device_node *node;
 	struct soc_device_attribute *soc_dev_attr;
-	struct device *dev = &pdev->dev;
 	struct soc_device *soc_dev;
-	struct regmap *regmap;
-	void __iomem *base;
 	u32 partno_id;
 	u32 variant;
-	u32 jtag_id;
 	u32 mfg;
 	int ret;
 
-	base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(base))
-		return PTR_ERR(base);
-
-	regmap = devm_regmap_init_mmio(dev, base, &k3_chipinfo_regmap_cfg);
-	if (IS_ERR(regmap))
-		return PTR_ERR(regmap);
-
-	ret = regmap_read(regmap, CTRLMMR_WKUP_JTAGID_REG, &jtag_id);
-	if (ret < 0)
-		return ret;
-
 	mfg = (jtag_id & CTRLMMR_WKUP_JTAGID_MFG_MASK) >>
 	       CTRLMMR_WKUP_JTAGID_MFG_SHIFT;
 
@@ -237,6 +229,36 @@ static int k3_chipinfo_probe(struct platform_device *pdev)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(k3_socinfo_register);
+
+static const struct regmap_config k3_chipinfo_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
+static int k3_chipinfo_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct regmap *regmap;
+	void __iomem *base;
+	u32 jtag_id;
+	int ret;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(dev, base, &k3_chipinfo_regmap_cfg);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, CTRLMMR_WKUP_JTAGID_REG, &jtag_id);
+	if (ret < 0)
+		return ret;
+
+	return k3_socinfo_register(dev, jtag_id);
+}
 
 static const struct of_device_id k3_chipinfo_of_match[] = {
 	{ .compatible = "ti,am654-chipid", },
diff --git a/include/linux/soc/ti/k3-socinfo.h b/include/linux/soc/ti/k3-socinfo.h
new file mode 100644
index 0000000000000..487e69d0069d1
--- /dev/null
+++ b/include/linux/soc/ti/k3-socinfo.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_SOC_TI_K3_SOCINFO_H__
+#define __LINUX_SOC_TI_K3_SOCINFO_H__
+
+#include <linux/types.h>
+
+struct device;
+
+int k3_socinfo_register(struct device *dev, u32 jtag_id);
+
+#endif /* __LINUX_SOC_TI_K3_SOCINFO_H__ */
-- 
2.34.1