1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Nuvoton WPCM450 SoC Identification
  4 *
  5 * Copyright (C) 2022 Jonathan Neuschäfer
  6 */
  7
  8#include <linux/mfd/syscon.h>
  9#include <linux/of.h>
 10#include <linux/regmap.h>
 11#include <linux/slab.h>
 12#include <linux/sys_soc.h>
 13
 14#define GCR_PDID	0
 15#define PDID_CHIP(x)	((x) & 0x00ffffff)
 16#define CHIP_WPCM450	0x926450
 17#define PDID_REV(x)	((x) >> 24)
 18
 19struct revision {
 20	u8 number;
 21	const char *name;
 22};
 23
 24static const struct revision revisions[] __initconst = {
 25	{ 0x00, "Z1" },
 26	{ 0x03, "Z2" },
 27	{ 0x04, "Z21" },
 28	{ 0x08, "A1" },
 29	{ 0x09, "A2" },
 30	{ 0x0a, "A3" },
 31	{}
 32};
 33
 34static const char * __init get_revision(unsigned int rev)
 35{
 36	int i;
 37
 38	for (i = 0; revisions[i].name; i++)
 39		if (revisions[i].number == rev)
 40			return revisions[i].name;
 41	return NULL;
 42}
 43
 44static struct soc_device_attribute *wpcm450_attr;
 45static struct soc_device *wpcm450_soc;
 46
 47static int __init wpcm450_soc_init(void)
 48{
 49	struct soc_device_attribute *attr;
 50	struct soc_device *soc;
 51	const char *revision;
 52	struct regmap *gcr;
 53	u32 pdid;
 54	int ret;
 55
 56	if (!of_machine_is_compatible("nuvoton,wpcm450"))
 57		return 0;
 58
 59	gcr = syscon_regmap_lookup_by_compatible("nuvoton,wpcm450-gcr");
 60	if (IS_ERR(gcr))
 61		return PTR_ERR(gcr);
 62	ret = regmap_read(gcr, GCR_PDID, &pdid);
 63	if (ret)
 64		return ret;
 65
 66	if (PDID_CHIP(pdid) != CHIP_WPCM450) {
 67		pr_warn("Unknown chip ID in GCR.PDID: 0x%06x\n", PDID_CHIP(pdid));
 68		return -ENODEV;
 69	}
 70
 71	revision = get_revision(PDID_REV(pdid));
 72	if (!revision) {
 73		pr_warn("Unknown chip revision in GCR.PDID: 0x%02x\n", PDID_REV(pdid));
 74		return -ENODEV;
 75	}
 76
 77	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 78	if (!attr)
 79		return -ENOMEM;
 80
 81	attr->family = "Nuvoton NPCM";
 82	attr->soc_id = "WPCM450";
 83	attr->revision = revision;
 84	soc = soc_device_register(attr);
 85	if (IS_ERR(soc)) {
 86		kfree(attr);
 87		pr_warn("Could not register SoC device\n");
 88		return PTR_ERR(soc);
 89	}
 90
 91	wpcm450_soc = soc;
 92	wpcm450_attr = attr;
 93	return 0;
 94}
 95module_init(wpcm450_soc_init);
 96
 97static void __exit wpcm450_soc_exit(void)
 98{
 99	if (wpcm450_soc) {
100		soc_device_unregister(wpcm450_soc);
101		wpcm450_soc = NULL;
102		kfree(wpcm450_attr);
103	}
104}
105module_exit(wpcm450_soc_exit);
106
107MODULE_LICENSE("GPL");
108MODULE_AUTHOR("Jonathan Neuschäfer");
109MODULE_DESCRIPTION("Nuvoton WPCM450 SoC Identification driver");