LXR linux/drivers/platform/chrome/cros_ec

   1/*
   2 * cros_ec_vbc - Expose the vboot context nvram to userspace
   3 *
   4 * Copyright (C) 2015 Collabora Ltd.
   5 *
   6 * based on vendor driver,
   7 *
   8 * Copyright (C) 2012 The Chromium OS Authors
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License as published by
  12 * the Free Software Foundation; either version 2 of the License, or
  13 * (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 */
  20
  21#include <linux/of.h>
  22#include <linux/platform_device.h>
  23#include <linux/mfd/cros_ec.h>
  24#include <linux/mfd/cros_ec_commands.h>
  25#include <linux/slab.h>
  26
  27static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
  28                                  struct bin_attribute *att, char *buf,
  29                                  loff_t pos, size_t count)
  30{
  31        struct device *dev = container_of(kobj, struct device, kobj);
  32        struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
  33                                              class_dev);
  34        struct cros_ec_device *ecdev = ec->ec_dev;
  35        struct ec_params_vbnvcontext *params;
  36        struct cros_ec_command *msg;
  37        int err;
  38        const size_t para_sz = sizeof(params->op);
  39        const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
  40        const size_t payload = max(para_sz, resp_sz);
  41
  42        msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
  43        if (!msg)
  44                return -ENOMEM;
  45
  46        /* NB: we only kmalloc()ated enough space for the op field */
  47        params = (struct ec_params_vbnvcontext *)msg->data;
  48        params->op = EC_VBNV_CONTEXT_OP_READ;
  49
  50        msg->version = EC_VER_VBNV_CONTEXT;
  51        msg->command = EC_CMD_VBNV_CONTEXT;
  52        msg->outsize = para_sz;
  53        msg->insize = resp_sz;
  54
  55        err = cros_ec_cmd_xfer(ecdev, msg);
  56        if (err < 0) {
  57                dev_err(dev, "Error sending read request: %d\n", err);
  58                kfree(msg);
  59                return err;
  60        }
  61
  62        memcpy(buf, msg->data, resp_sz);
  63
  64        kfree(msg);
  65        return resp_sz;
  66}
  67
  68static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
  69                                   struct bin_attribute *attr, char *buf,
  70                                   loff_t pos, size_t count)
  71{
  72        struct device *dev = container_of(kobj, struct device, kobj);
  73        struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
  74                                              class_dev);
  75        struct cros_ec_device *ecdev = ec->ec_dev;
  76        struct ec_params_vbnvcontext *params;
  77        struct cros_ec_command *msg;
  78        int err;
  79        const size_t para_sz = sizeof(*params);
  80        const size_t data_sz = sizeof(params->block);
  81
  82        /* Only write full values */
  83        if (count != data_sz)
  84                return -EINVAL;
  85
  86        msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
  87        if (!msg)
  88                return -ENOMEM;
  89
  90        params = (struct ec_params_vbnvcontext *)msg->data;
  91        params->op = EC_VBNV_CONTEXT_OP_WRITE;
  92        memcpy(params->block, buf, data_sz);
  93
  94        msg->version = EC_VER_VBNV_CONTEXT;
  95        msg->command = EC_CMD_VBNV_CONTEXT;
  96        msg->outsize = para_sz;
  97        msg->insize = 0;
  98
  99        err = cros_ec_cmd_xfer(ecdev, msg);
 100        if (err < 0) {
 101                dev_err(dev, "Error sending write request: %d\n", err);
 102                kfree(msg);
 103                return err;
 104        }
 105
 106        kfree(msg);
 107        return data_sz;
 108}
 109
 110static umode_t cros_ec_vbc_is_visible(struct kobject *kobj,
 111                                      struct bin_attribute *a, int n)
 112{
 113        struct device *dev = container_of(kobj, struct device, kobj);
 114        struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
 115                                              class_dev);
 116        struct device_node *np = ec->ec_dev->dev->of_node;
 117
 118        if (IS_ENABLED(CONFIG_OF) && np) {
 119                if (of_property_read_bool(np, "google,has-vbc-nvram"))
 120                        return a->attr.mode;
 121        }
 122
 123        return 0;
 124}
 125
 126static BIN_ATTR_RW(vboot_context, 16);
 127
 128static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
 129        &bin_attr_vboot_context,
 130        NULL
 131};
 132
 133struct attribute_group cros_ec_vbc_attr_group = {
 134        .name = "vbc",
 135        .bin_attrs = cros_ec_vbc_bin_attrs,
 136        .is_bin_visible = cros_ec_vbc_is_visible,
 137};
 138