1 // SPDX-License-Identifier: GPL-2.0+ 2 // Expose the vboot context nvram to userspace 3 // 4 // Copyright (C) 2012 Google, Inc. 5 // Copyright (C) 2015 Collabora Ltd. 6 7 #include <linux/of.h> 8 #include <linux/platform_device.h> 9 #include <linux/module.h> 10 #include <linux/platform_data/cros_ec_commands.h> 11 #include <linux/platform_data/cros_ec_proto.h> 12 #include <linux/slab.h> 13 14 #define DRV_NAME "cros-ec-vbc" 15 16 static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj, 17 struct bin_attribute *att, char *buf, 18 loff_t pos, size_t count) 19 { 20 struct device *dev = kobj_to_dev(kobj); 21 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 22 struct cros_ec_device *ecdev = ec->ec_dev; 23 struct cros_ec_command *msg; 24 /* 25 * This should be a pointer to the same type as op field in 26 * struct ec_params_vbnvcontext. 27 */ 28 uint32_t *params_op; 29 int err; 30 const size_t para_sz = sizeof(*params_op); 31 const size_t resp_sz = sizeof(struct ec_response_vbnvcontext); 32 const size_t payload = max(para_sz, resp_sz); 33 34 msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL); 35 if (!msg) 36 return -ENOMEM; 37 38 /* NB: we only kmalloc()ated enough space for the op field */ 39 params_op = (uint32_t *)msg->data; 40 *params_op = EC_VBNV_CONTEXT_OP_READ; 41 42 msg->version = EC_VER_VBNV_CONTEXT; 43 msg->command = EC_CMD_VBNV_CONTEXT; 44 msg->outsize = para_sz; 45 msg->insize = resp_sz; 46 47 err = cros_ec_cmd_xfer_status(ecdev, msg); 48 if (err < 0) { 49 dev_err(dev, "Error sending read request: %d\n", err); 50 kfree(msg); 51 return err; 52 } 53 54 memcpy(buf, msg->data, resp_sz); 55 56 kfree(msg); 57 return resp_sz; 58 } 59 60 static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj, 61 struct bin_attribute *attr, char *buf, 62 loff_t pos, size_t count) 63 { 64 struct device *dev = kobj_to_dev(kobj); 65 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 66 struct cros_ec_device *ecdev = ec->ec_dev; 67 struct ec_params_vbnvcontext *params; 68 struct cros_ec_command *msg; 69 int err; 70 const size_t para_sz = sizeof(*params); 71 const size_t data_sz = sizeof(params->block); 72 73 /* Only write full values */ 74 if (count != data_sz) 75 return -EINVAL; 76 77 msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL); 78 if (!msg) 79 return -ENOMEM; 80 81 params = (struct ec_params_vbnvcontext *)msg->data; 82 params->op = EC_VBNV_CONTEXT_OP_WRITE; 83 memcpy(params->block, buf, data_sz); 84 85 msg->version = EC_VER_VBNV_CONTEXT; 86 msg->command = EC_CMD_VBNV_CONTEXT; 87 msg->outsize = para_sz; 88 msg->insize = 0; 89 90 err = cros_ec_cmd_xfer_status(ecdev, msg); 91 if (err < 0) { 92 dev_err(dev, "Error sending write request: %d\n", err); 93 kfree(msg); 94 return err; 95 } 96 97 kfree(msg); 98 return data_sz; 99 } 100 101 static BIN_ATTR_RW(vboot_context, 16); 102 103 static struct bin_attribute *cros_ec_vbc_bin_attrs[] = { 104 &bin_attr_vboot_context, 105 NULL 106 }; 107 108 static const struct attribute_group cros_ec_vbc_attr_group = { 109 .name = "vbc", 110 .bin_attrs = cros_ec_vbc_bin_attrs, 111 }; 112 113 static int cros_ec_vbc_probe(struct platform_device *pd) 114 { 115 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 116 struct device *dev = &pd->dev; 117 int ret; 118 119 ret = sysfs_create_group(&ec_dev->class_dev.kobj, 120 &cros_ec_vbc_attr_group); 121 if (ret < 0) 122 dev_err(dev, "failed to create %s attributes. err=%d\n", 123 cros_ec_vbc_attr_group.name, ret); 124 125 return ret; 126 } 127 128 static void cros_ec_vbc_remove(struct platform_device *pd) 129 { 130 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 131 132 sysfs_remove_group(&ec_dev->class_dev.kobj, 133 &cros_ec_vbc_attr_group); 134 } 135 136 static struct platform_driver cros_ec_vbc_driver = { 137 .driver = { 138 .name = DRV_NAME, 139 }, 140 .probe = cros_ec_vbc_probe, 141 .remove_new = cros_ec_vbc_remove, 142 }; 143 144 module_platform_driver(cros_ec_vbc_driver); 145 146 MODULE_LICENSE("GPL"); 147 MODULE_DESCRIPTION("Expose the vboot context nvram to userspace"); 148 MODULE_ALIAS("platform:" DRV_NAME); 149