[PATCH v3 3/4] platform/chrome: Support reading/writing the vboot context
Emilio López
emilio.lopez at collabora.co.uk
Mon Sep 21 06:38:22 PDT 2015
Some EC implementations include a small nvram space used to store
verified boot context data. This patch offers a way to expose this
data to userspace.
Reviewed-by: Javier Martinez Canillas <javier at osg.samsung.com>
Signed-off-by: Emilio López <emilio.lopez at collabora.co.uk>
---
Changes from v1:
- Use is_bin_visible instead of is_visible
Changes from v2:
- Changes suggested by Javier (makefile, size checks, etc)
- Add his reviewed-by
drivers/platform/chrome/Makefile | 3 +-
drivers/platform/chrome/cros_ec_dev.c | 1 +
drivers/platform/chrome/cros_ec_vbc.c | 137 ++++++++++++++++++++++++++++++++++
include/linux/mfd/cros_ec.h | 1 +
4 files changed, 141 insertions(+), 1 deletion(-)
create mode 100644 drivers/platform/chrome/cros_ec_vbc.c
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 4a11b01..bc498bd 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -1,7 +1,8 @@
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
-cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o cros_ec_lightbar.o
+cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o \
+ cros_ec_lightbar.o cros_ec_vbc.o
obj-$(CONFIG_CROS_EC_CHARDEV) += cros_ec_devs.o
obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpc.o
obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o
diff --git a/drivers/platform/chrome/cros_ec_dev.c b/drivers/platform/chrome/cros_ec_dev.c
index e8fcdc2..d19263f 100644
--- a/drivers/platform/chrome/cros_ec_dev.c
+++ b/drivers/platform/chrome/cros_ec_dev.c
@@ -32,6 +32,7 @@ static int ec_major;
static const struct attribute_group *cros_ec_groups[] = {
&cros_ec_attr_group,
&cros_ec_lightbar_attr_group,
+ &cros_ec_vbc_attr_group,
NULL,
};
diff --git a/drivers/platform/chrome/cros_ec_vbc.c b/drivers/platform/chrome/cros_ec_vbc.c
new file mode 100644
index 0000000..564a0d0
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_vbc.c
@@ -0,0 +1,137 @@
+/*
+ * cros_ec_vbc - Expose the vboot context nvram to userspace
+ *
+ * Copyright (C) 2015 Collabora Ltd.
+ *
+ * based on vendor driver,
+ *
+ * Copyright (C) 2012 The Chromium OS Authors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/slab.h>
+
+static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *att, char *buf,
+ loff_t pos, size_t count)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
+ class_dev);
+ struct cros_ec_device *ecdev = ec->ec_dev;
+ struct ec_params_vbnvcontext *params;
+ struct cros_ec_command *msg;
+ int err;
+ const size_t para_sz = sizeof(params->op);
+ const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
+ const size_t payload = max(para_sz, resp_sz);
+
+ msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ /* NB: we only kmalloc()ated enough space for the op field */
+ params = (struct ec_params_vbnvcontext *)msg->data;
+ params->op = EC_VBNV_CONTEXT_OP_READ;
+
+ msg->version = EC_VER_VBNV_CONTEXT;
+ msg->command = EC_CMD_VBNV_CONTEXT;
+ msg->outsize = para_sz;
+ msg->insize = resp_sz;
+
+ err = cros_ec_cmd_xfer(ecdev, msg);
+ if (err < 0) {
+ dev_err(dev, "Error sending read request: %d\n", err);
+ kfree(msg);
+ return err;
+ }
+
+ memcpy(buf, msg->data, resp_sz);
+
+ kfree(msg);
+ return resp_sz;
+}
+
+static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *attr, char *buf,
+ loff_t pos, size_t count)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
+ class_dev);
+ struct cros_ec_device *ecdev = ec->ec_dev;
+ struct ec_params_vbnvcontext *params;
+ struct cros_ec_command *msg;
+ int err;
+ const size_t para_sz = sizeof(*params);
+ const size_t data_sz = sizeof(params->block);
+
+ /* Only write full values */
+ if (count != data_sz)
+ return -EINVAL;
+
+ msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ params = (struct ec_params_vbnvcontext *)msg->data;
+ params->op = EC_VBNV_CONTEXT_OP_WRITE;
+ memcpy(params->block, buf, data_sz);
+
+ msg->version = EC_VER_VBNV_CONTEXT;
+ msg->command = EC_CMD_VBNV_CONTEXT;
+ msg->outsize = para_sz;
+ msg->insize = 0;
+
+ err = cros_ec_cmd_xfer(ecdev, msg);
+ if (err < 0) {
+ dev_err(dev, "Error sending write request: %d\n", err);
+ kfree(msg);
+ return err;
+ }
+
+ kfree(msg);
+ return data_sz;
+}
+
+static umode_t cros_ec_vbc_is_visible(struct kobject *kobj,
+ struct bin_attribute *a, int n)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
+ class_dev);
+ struct device_node *np = ec->ec_dev->dev->of_node;
+
+ if (IS_ENABLED(CONFIG_OF) && np) {
+ if (of_property_read_bool(np, "google,has-vbc-nvram"))
+ return a->attr.mode;
+ }
+
+ return 0;
+}
+
+static BIN_ATTR_RW(vboot_context, 16);
+
+static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
+ &bin_attr_vboot_context,
+ NULL
+};
+
+struct attribute_group cros_ec_vbc_attr_group = {
+ .name = "vbc",
+ .bin_attrs = cros_ec_vbc_bin_attrs,
+ .is_bin_visible = cros_ec_vbc_is_visible,
+};
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index da72671..494682c 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -255,5 +255,6 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev);
/* sysfs stuff */
extern struct attribute_group cros_ec_attr_group;
extern struct attribute_group cros_ec_lightbar_attr_group;
+extern struct attribute_group cros_ec_vbc_attr_group;
#endif /* __LINUX_MFD_CROS_EC_H */
--
2.1.4
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