linux-kernel - [PATCH 01/12] of: Add of_get_cpu_hwid() to read hardware ID from CPU nodes

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Message-Id: <20211006164332.1981454-2-robh@kernel.org>
Date:   Wed,  6 Oct 2021 11:43:21 -0500
From:   Rob Herring <robh@...nel.org>
To:     Russell King <linux@...linux.org.uk>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, x86@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-csky@...r.kernel.org, openrisc@...ts.librecores.org,
        linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
        linux-sh@...r.kernel.org, devicetree@...r.kernel.org
Subject: [PATCH 01/12] of: Add of_get_cpu_hwid() to read hardware ID from CPU nodes

There are various open coded implementions parsing the CPU node 'reg'
property which contains the CPU's hardware ID. Introduce a new function,
of_get_cpu_hwid(), to read the hardware ID.

All the callers should be DT only code, so no need for an empty
function.

Cc: Frank Rowand <frowand.list@...il.com>
Signed-off-by: Rob Herring <robh@...nel.org>
---
 drivers/of/base.c  | 22 ++++++++++++++++++++++
 include/linux/of.h |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f720c0d246f2..e587ab44be22 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -286,6 +286,28 @@ const void *of_get_property(const struct device_node *np, const char *name,
 }
 EXPORT_SYMBOL(of_get_property);
 
+/**
+ * of_get_cpu_hwid - Get the hardware ID from a CPU device node
+ *
+ * @cpun: CPU number(logical index) for which device node is required
+ * @thread: The local thread number to get the hardware ID for.
+ *
+ * Return: The hardware ID for the CPU node or ~0ULL if not found.
+ */
+u64 of_get_cpu_hwid(struct device_node *cpun, unsigned int thread)
+{
+	const __be32 *cell;
+	int ac, len;
+
+	ac = of_n_addr_cells(cpun);
+	cell = of_get_property(cpun, "reg", &len);
+	if (!cell || !ac || ((sizeof(*cell) * ac * (thread + 1)) > len))
+		return ~0ULL;
+
+	cell += ac * thread;
+	return of_read_number(cell, ac);
+}
+
 /*
  * arch_match_cpu_phys_id - Match the given logical CPU and physical id
  *
diff --git a/include/linux/of.h b/include/linux/of.h
index 6f1c41f109bb..807f8168dad9 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -353,6 +353,7 @@ extern struct device_node *of_get_cpu_node(int cpu, unsigned int *thread);
 extern struct device_node *of_get_next_cpu_node(struct device_node *prev);
 extern struct device_node *of_get_cpu_state_node(struct device_node *cpu_node,
 						 int index);
+extern u64 of_get_cpu_hwid(struct device_node *cpun, unsigned int thread);
 
 #define for_each_property_of_node(dn, pp) \
 	for (pp = dn->properties; pp != NULL; pp = pp->next)
-- 
2.30.2