linux-kernel - [PATCH] firmware: vpd: Add an interface to read VPD value

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Message-Id: <20191007071610.65714-1-cychiang@chromium.org>
Date:   Mon,  7 Oct 2019 15:16:10 +0800
From:   Cheng-Yi Chiang <cychiang@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     alsa-devel@...a-project.org, Guenter Roeck <linux@...ck-us.net>,
        Hung-Te Lin <hungte@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sean Paul <seanpaul@...omium.org>,
        Mark Brown <broonie@...nel.org>,
        Cheng-Yi Chiang <cychiang@...omium.org>, dgreid@...omium.org,
        tzungbi@...omium.org
Subject: [PATCH] firmware: vpd: Add an interface to read VPD value

Add an interface for other driver to query VPD value.
This will be used for ASoC machine driver to query calibration
data stored in VPD for smart amplifier speaker resistor
calibration.

Signed-off-by: Cheng-Yi Chiang <cychiang@...omium.org>
---
 drivers/firmware/google/vpd.c              | 16 ++++++++++++++++
 include/linux/firmware/google/google_vpd.h | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/linux/firmware/google/google_vpd.h

diff --git a/drivers/firmware/google/vpd.c b/drivers/firmware/google/vpd.c
index db0812263d46..71e9d2da63be 100644
--- a/drivers/firmware/google/vpd.c
+++ b/drivers/firmware/google/vpd.c
@@ -65,6 +65,22 @@ static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
 				       info->bin_attr.size);
 }
 
+int vpd_attribute_read_value(bool ro, const char *key,
+			     char **value, u32 value_len)
+{
+	struct vpd_attrib_info *info;
+	struct vpd_section *sec = ro ? &ro_vpd : &rw_vpd;
+
+	list_for_each_entry(info, &sec->attribs, list) {
+		if (strcmp(info->key, key) == 0) {
+			*value = kstrndup(info->value, value_len, GFP_KERNEL);
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vpd_attribute_read_value);
+
 /*
  * vpd_section_check_key_name()
  *
diff --git a/include/linux/firmware/google/google_vpd.h b/include/linux/firmware/google/google_vpd.h
new file mode 100644
index 000000000000..6f1160f28af8
--- /dev/null
+++ b/include/linux/firmware/google/google_vpd.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Google VPD interface.
+ *
+ * Copyright 2019 Google Inc.
+ */
+
+/* Interface for reading VPD value on Chrome platform. */
+
+#ifndef __GOOGLE_VPD_H
+#define __GOOGLE_VPD_H
+
+#include <linux/types.h>
+
+int vpd_attribute_read_value(bool ro, const char *key,
+			     char **value, u32 value_len);
+
+#endif  /* __GOOGLE_VPD_H */
-- 
2.23.0.581.g78d2f28ef7-goog