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Message-ID: <CABxcv=m23sfK=jOCswirQRB1SbP70VnomKp6hhwFhRLHiabq4w@mail.gmail.com>
Date: Tue, 15 Sep 2015 15:47:57 +0200
From: Javier Martinez Canillas <javier@...hile0.org>
To: Emilio López <emilio.lopez@...labora.co.uk>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Olof Johansson <olof@...om.net>, Kukjin Kim <kgene@...nel.org>,
Krzysztof Kozłowski <k.kozlowski@...sung.com>,
Guenter Roeck <linux@...ck-us.net>,
Linux Kernel <linux-kernel@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-samsung-soc@...r.kernel.org"
<linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] platform/chrome: Support reading/writing the vboot context
Hello Emilio,
Patch looks mostly good to me, I just have a few comments.
On Mon, Sep 14, 2015 at 2:34 PM, Emilio López
<emilio.lopez@...labora.co.uk> wrote:
> 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.
>
> Signed-off-by: Emilio López <emilio.lopez@...labora.co.uk>
> ---
> Changes from v1:
> - Use is_bin_visible instead of is_visible
>
> Documentation/devicetree/bindings/mfd/cros-ec.txt | 4 +
> drivers/platform/chrome/Makefile | 5 +-
> drivers/platform/chrome/cros_ec_dev.c | 1 +
> drivers/platform/chrome/cros_ec_vbc.c | 137 ++++++++++++++++++++++
> include/linux/mfd/cros_ec.h | 1 +
> 5 files changed, 147 insertions(+), 1 deletion(-)
> create mode 100644 drivers/platform/chrome/cros_ec_vbc.c
>
> diff --git a/Documentation/devicetree/bindings/mfd/cros-ec.txt b/Documentation/devicetree/bindings/mfd/cros-ec.txt
> index 1777916..136e0c2 100644
> --- a/Documentation/devicetree/bindings/mfd/cros-ec.txt
> +++ b/Documentation/devicetree/bindings/mfd/cros-ec.txt
> @@ -34,6 +34,10 @@ Required properties (LPC):
> - compatible: "google,cros-ec-lpc"
> - reg: List of (IO address, size) pairs defining the interface uses
>
> +Optional properties (all):
> +- google,has-vbc-nvram: Some implementations of the EC include a small
> + nvram space used to store verified boot context data. This boolean flag
> + is used to specify whether this nvram is present or not.
>
> Example for I2C:
>
I would split the DT binding part from the actual implementation, see
Documentation/devicetree/bindings/submitting-patches.txt.
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 4a11b01..787be61 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -1,7 +1,10 @@
>
> 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_devs-objs += cros_ec_lightbar.o
> +cros_ec_devs-objs += cros_ec_sysfs.o
> +cros_ec_devs-objs += cros_ec_vbc.o
Why are you changing the Makefile? AFAIK += is usually used when the
compilation is conditional based on a Kconfig symbol but since these
are build unconditionally, I'll just keep it as foo := bar baz
Which makes me think, do we need a Kconfig option for this feature
since not all machines have it?
> 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..a0e8d38
> --- /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(struct ec_params_vbnvcontext);
> + 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;
> +
> + 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 = sizeof(params->op);
Shouldn't this be para_sz ? Since you are sending to the EC the whole
struct ec_params_vbnvcontext and not only the op field.
Or if the EC only expects to get the u32 op field, then I think your
max payload calculation is not correct.
> + 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;
> + }
> +
> + BUILD_BUG_ON(resp_sz > PAGE_SIZE);
Why you need this? struct ec_response_vbnvcontext is really small AFAICT.
> + 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
Best regards,
Javier
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