ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 416 insertions, 0 deletions

diff --git a/drivers/soc/atmel/soc.c b/drivers/soc/atmel/soc.c
new file mode 100644
index 000000000..d89f9dcad
--- /dev/null
+++ b/drivers/soc/atmel/soc.c
@@ -0,0 +1,416 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2015 Atmel
+ *
+ * Alexandre Belloni <alexandre.belloni@free-electrons.com
+ * Boris Brezillon <boris.brezillon@free-electrons.com
+ */
+
+#define pr_fmt(fmt)	"AT91: " fmt
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#include "soc.h"
+
+#define AT91_DBGU_CIDR			0x40
+#define AT91_DBGU_EXID			0x44
+#define AT91_CHIPID_CIDR		0x00
+#define AT91_CHIPID_EXID		0x04
+#define AT91_CIDR_VERSION(x, m)		((x) & (m))
+#define AT91_CIDR_VERSION_MASK		GENMASK(4, 0)
+#define AT91_CIDR_VERSION_MASK_SAMA7G5	GENMASK(3, 0)
+#define AT91_CIDR_EXT			BIT(31)
+#define AT91_CIDR_MATCH_MASK		GENMASK(30, 5)
+#define AT91_CIDR_MASK_SAMA7G5		GENMASK(27, 5)
+
+static const struct at91_soc socs[] __initconst = {
+#ifdef CONFIG_SOC_AT91RM9200
+	AT91_SOC(AT91RM9200_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91rm9200 BGA", "at91rm9200"),
+#endif
+#ifdef CONFIG_SOC_AT91SAM9
+	AT91_SOC(AT91SAM9260_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9260", NULL),
+	AT91_SOC(AT91SAM9261_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9261", NULL),
+	AT91_SOC(AT91SAM9263_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9263", NULL),
+	AT91_SOC(AT91SAM9G20_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9g20", NULL),
+	AT91_SOC(AT91SAM9RL64_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9rl64", NULL),
+	AT91_SOC(AT91SAM9G45_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9M11_EXID_MATCH,
+		 "at91sam9m11", "at91sam9g45"),
+	AT91_SOC(AT91SAM9G45_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9M10_EXID_MATCH,
+		 "at91sam9m10", "at91sam9g45"),
+	AT91_SOC(AT91SAM9G45_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9G46_EXID_MATCH,
+		 "at91sam9g46", "at91sam9g45"),
+	AT91_SOC(AT91SAM9G45_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9G45_EXID_MATCH,
+		 "at91sam9g45", "at91sam9g45"),
+	AT91_SOC(AT91SAM9X5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9G15_EXID_MATCH,
+		 "at91sam9g15", "at91sam9x5"),
+	AT91_SOC(AT91SAM9X5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9G35_EXID_MATCH,
+		 "at91sam9g35", "at91sam9x5"),
+	AT91_SOC(AT91SAM9X5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9X35_EXID_MATCH,
+		 "at91sam9x35", "at91sam9x5"),
+	AT91_SOC(AT91SAM9X5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9G25_EXID_MATCH,
+		 "at91sam9g25", "at91sam9x5"),
+	AT91_SOC(AT91SAM9X5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9X25_EXID_MATCH,
+		 "at91sam9x25", "at91sam9x5"),
+	AT91_SOC(AT91SAM9N12_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9CN12_EXID_MATCH,
+		 "at91sam9cn12", "at91sam9n12"),
+	AT91_SOC(AT91SAM9N12_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9N12_EXID_MATCH,
+		 "at91sam9n12", "at91sam9n12"),
+	AT91_SOC(AT91SAM9N12_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, AT91SAM9CN11_EXID_MATCH,
+		 "at91sam9cn11", "at91sam9n12"),
+	AT91_SOC(AT91SAM9XE128_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9xe128", "at91sam9xe128"),
+	AT91_SOC(AT91SAM9XE256_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9xe256", "at91sam9xe256"),
+	AT91_SOC(AT91SAM9XE512_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, 0, "at91sam9xe512", "at91sam9xe512"),
+#endif
+#ifdef CONFIG_SOC_SAM9X60
+	AT91_SOC(SAM9X60_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X60_EXID_MATCH,
+		 "sam9x60", "sam9x60"),
+	AT91_SOC(SAM9X60_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X60_D5M_EXID_MATCH,
+		 "sam9x60 64MiB DDR2 SiP", "sam9x60"),
+	AT91_SOC(SAM9X60_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X60_D1G_EXID_MATCH,
+		 "sam9x60 128MiB DDR2 SiP", "sam9x60"),
+	AT91_SOC(SAM9X60_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X60_D6K_EXID_MATCH,
+		 "sam9x60 8MiB SDRAM SiP", "sam9x60"),
+#endif
+#ifdef CONFIG_SOC_SAM9X7
+	AT91_SOC(SAM9X7_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X70_EXID_MATCH,
+		 "sam9x70", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X72_EXID_MATCH,
+		 "sam9x72", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAM9X75_EXID_MATCH,
+		 "sam9x75", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, SAM9X75_D1M_EXID_MATCH,
+		 AT91_CIDR_VERSION_MASK, SAM9X75_EXID_MATCH,
+		 "sam9x75 16MB DDR2 SiP", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, SAM9X75_D5M_EXID_MATCH,
+		 AT91_CIDR_VERSION_MASK, SAM9X75_EXID_MATCH,
+		 "sam9x75 64MB DDR2 SiP", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, SAM9X75_D1G_EXID_MATCH,
+		 AT91_CIDR_VERSION_MASK, SAM9X75_EXID_MATCH,
+		 "sam9x75 125MB DDR3L SiP ", "sam9x7"),
+	AT91_SOC(SAM9X7_CIDR_MATCH, SAM9X75_D2G_EXID_MATCH,
+		 AT91_CIDR_VERSION_MASK, SAM9X75_EXID_MATCH,
+		 "sam9x75 250MB DDR3L SiP", "sam9x7"),
+#endif
+#ifdef CONFIG_SOC_SAMA5
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D21CU_EXID_MATCH,
+		 "sama5d21", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D22CU_EXID_MATCH,
+		 "sama5d22", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D225C_D1M_EXID_MATCH,
+		 "sama5d225c 16MiB SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D23CU_EXID_MATCH,
+		 "sama5d23", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D24CX_EXID_MATCH,
+		 "sama5d24", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D24CU_EXID_MATCH,
+		 "sama5d24", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D26CU_EXID_MATCH,
+		 "sama5d26", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27CU_EXID_MATCH,
+		 "sama5d27", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27CN_EXID_MATCH,
+		 "sama5d27", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27C_D1G_EXID_MATCH,
+		 "sama5d27c 128MiB SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27C_D5M_EXID_MATCH,
+		 "sama5d27c 64MiB SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27C_LD1G_EXID_MATCH,
+		 "sama5d27c 128MiB LPDDR2 SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D27C_LD2G_EXID_MATCH,
+		 "sama5d27c 256MiB LPDDR2 SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D28CU_EXID_MATCH,
+		 "sama5d28", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D28CN_EXID_MATCH,
+		 "sama5d28", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D28C_D1G_EXID_MATCH,
+		 "sama5d28c 128MiB SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D28C_LD1G_EXID_MATCH,
+		 "sama5d28c 128MiB LPDDR2 SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D28C_LD2G_EXID_MATCH,
+		 "sama5d28c 256MiB LPDDR2 SiP", "sama5d2"),
+	AT91_SOC(SAMA5D2_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D29CN_EXID_MATCH,
+		 "sama5d29", "sama5d2"),
+	AT91_SOC(SAMA5D3_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D31_EXID_MATCH,
+		 "sama5d31", "sama5d3"),
+	AT91_SOC(SAMA5D3_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D33_EXID_MATCH,
+		 "sama5d33", "sama5d3"),
+	AT91_SOC(SAMA5D3_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D34_EXID_MATCH,
+		 "sama5d34", "sama5d3"),
+	AT91_SOC(SAMA5D3_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D35_EXID_MATCH,
+		 "sama5d35", "sama5d3"),
+	AT91_SOC(SAMA5D3_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D36_EXID_MATCH,
+		 "sama5d36", "sama5d3"),
+	AT91_SOC(SAMA5D4_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D41_EXID_MATCH,
+		 "sama5d41", "sama5d4"),
+	AT91_SOC(SAMA5D4_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D42_EXID_MATCH,
+		 "sama5d42", "sama5d4"),
+	AT91_SOC(SAMA5D4_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D43_EXID_MATCH,
+		 "sama5d43", "sama5d4"),
+	AT91_SOC(SAMA5D4_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMA5D44_EXID_MATCH,
+		 "sama5d44", "sama5d4"),
+#endif
+#ifdef CONFIG_SOC_SAMV7
+	AT91_SOC(SAME70Q21_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAME70Q21_EXID_MATCH,
+		 "same70q21", "same7"),
+	AT91_SOC(SAME70Q20_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAME70Q20_EXID_MATCH,
+		 "same70q20", "same7"),
+	AT91_SOC(SAME70Q19_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAME70Q19_EXID_MATCH,
+		 "same70q19", "same7"),
+	AT91_SOC(SAMS70Q21_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMS70Q21_EXID_MATCH,
+		 "sams70q21", "sams7"),
+	AT91_SOC(SAMS70Q20_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMS70Q20_EXID_MATCH,
+		 "sams70q20", "sams7"),
+	AT91_SOC(SAMS70Q19_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMS70Q19_EXID_MATCH,
+		 "sams70q19", "sams7"),
+	AT91_SOC(SAMV71Q21_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMV71Q21_EXID_MATCH,
+		 "samv71q21", "samv7"),
+	AT91_SOC(SAMV71Q20_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMV71Q20_EXID_MATCH,
+		 "samv71q20", "samv7"),
+	AT91_SOC(SAMV71Q19_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMV71Q19_EXID_MATCH,
+		 "samv71q19", "samv7"),
+	AT91_SOC(SAMV70Q20_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMV70Q20_EXID_MATCH,
+		 "samv70q20", "samv7"),
+	AT91_SOC(SAMV70Q19_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK, SAMV70Q19_EXID_MATCH,
+		 "samv70q19", "samv7"),
+#endif
+#ifdef CONFIG_SOC_SAMA7
+	AT91_SOC(SAMA7D65_CIDR_MATCH, AT91_CIDR_MASK_SAMA7G5,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7D65_EXID_MATCH,
+		 "sama7d65", "sama7d6"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G51_EXID_MATCH,
+		 "sama7g51", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G52_EXID_MATCH,
+		 "sama7g52", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G53_EXID_MATCH,
+		 "sama7g53", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G54_EXID_MATCH,
+		 "sama7g54", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G54_D1G_EXID_MATCH,
+		 "SAMA7G54 1Gb DDR3L SiP", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G54_D2G_EXID_MATCH,
+		 "SAMA7G54 2Gb DDR3L SiP", "sama7g5"),
+	AT91_SOC(SAMA7G5_CIDR_MATCH, AT91_CIDR_MATCH_MASK,
+		 AT91_CIDR_VERSION_MASK_SAMA7G5, SAMA7G54_D4G_EXID_MATCH,
+		 "SAMA7G54 4Gb DDR3L SiP", "sama7g5"),
+#endif
+	{ /* sentinel */ },
+};
+
+static int __init at91_get_cidr_exid_from_dbgu(u32 *cidr, u32 *exid)
+{
+	struct device_node *np;
+	void __iomem *regs;
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,at91rm9200-dbgu");
+	if (!np)
+		np = of_find_compatible_node(NULL, NULL,
+					     "atmel,at91sam9260-dbgu");
+	if (!np)
+		return -ENODEV;
+
+	regs = of_iomap(np, 0);
+	of_node_put(np);
+
+	if (!regs) {
+		pr_warn("Could not map DBGU iomem range");
+		return -ENXIO;
+	}
+
+	*cidr = readl(regs + AT91_DBGU_CIDR);
+	*exid = readl(regs + AT91_DBGU_EXID);
+
+	iounmap(regs);
+
+	return 0;
+}
+
+static int __init at91_get_cidr_exid_from_chipid(u32 *cidr, u32 *exid)
+{
+	struct device_node *np;
+	void __iomem *regs;
+	static const struct of_device_id chipids[] = {
+		{ .compatible = "atmel,sama5d2-chipid" },
+		{ .compatible = "microchip,sama7d65-chipid" },
+		{ .compatible = "microchip,sama7g5-chipid" },
+		{ },
+	};
+
+	np = of_find_matching_node(NULL, chipids);
+	if (!np)
+		return -ENODEV;
+
+	regs = of_iomap(np, 0);
+	of_node_put(np);
+
+	if (!regs) {
+		pr_warn("Could not map DBGU iomem range");
+		return -ENXIO;
+	}
+
+	*cidr = readl(regs + AT91_CHIPID_CIDR);
+	*exid = readl(regs + AT91_CHIPID_EXID);
+
+	iounmap(regs);
+
+	return 0;
+}
+
+struct soc_device * __init at91_soc_init(const struct at91_soc *socs)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	const struct at91_soc *soc;
+	struct soc_device *soc_dev;
+	u32 cidr, exid;
+	int ret;
+
+	/*
+	 * With SAMA5D2 and later SoCs, CIDR and EXID registers are no more
+	 * in the dbgu device but in the chipid device whose purpose is only
+	 * to expose these two registers.
+	 */
+	ret = at91_get_cidr_exid_from_dbgu(&cidr, &exid);
+	if (ret)
+		ret = at91_get_cidr_exid_from_chipid(&cidr, &exid);
+	if (ret) {
+		if (ret == -ENODEV)
+			pr_warn("Could not find identification node");
+		return NULL;
+	}
+
+	for (soc = socs; soc->name; soc++) {
+		if (soc->cidr_match != (cidr & soc->cidr_mask))
+			continue;
+
+		if (!(cidr & AT91_CIDR_EXT) || soc->exid_match == exid)
+			break;
+	}
+
+	if (!soc->name) {
+		pr_warn("Could not find matching SoC description\n");
+		return NULL;
+	}
+
+	soc_dev_attr = kzalloc_obj(*soc_dev_attr);
+	if (!soc_dev_attr)
+		return NULL;
+
+	soc_dev_attr->family = soc->family;
+	soc_dev_attr->soc_id = soc->name;
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%X",
+					   AT91_CIDR_VERSION(cidr, soc->version_mask));
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->revision);
+		kfree(soc_dev_attr);
+		pr_warn("Could not register SoC device\n");
+		return NULL;
+	}
+
+	if (soc->family)
+		pr_info("Detected SoC family: %s\n", soc->family);
+	pr_info("Detected SoC: %s, revision %X\n", soc->name,
+		AT91_CIDR_VERSION(cidr, soc->version_mask));
+
+	return soc_dev;
+}
+
+static const struct of_device_id at91_soc_allowed_list[] __initconst = {
+	{ .compatible = "atmel,at91rm9200", },
+	{ .compatible = "atmel,at91sam9", },
+	{ .compatible = "atmel,sama5", },
+	{ .compatible = "atmel,samv7", },
+	{ .compatible = "microchip,sama7d65", },
+	{ .compatible = "microchip,sama7g5", },
+	{ }
+};
+
+static int __init atmel_soc_device_init(void)
+{
+	struct device_node *np __free(device_node) = of_find_node_by_path("/");
+
+	if (!of_match_node(at91_soc_allowed_list, np))
+		return 0;
+
+	at91_soc_init(socs);
+
+	return 0;
+}
+subsys_initcall(atmel_soc_device_init);