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linux/drivers/rtc/rtc-optee.c
Clément Léger 81c2f059ab rtc: optee: add RTC driver for OP-TEE RTC PTA 
This drivers allows to communicate with a RTC PTA handled by OP-TEE [1].
This PTA allows to query RTC information, set/get time and set/get
offset depending on the supported features.

[1] https://github.com/OP-TEE/optee_os/pull/5179

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220308133505.471601-1-clement.leger@bootlin.com
2022-03-25 11:42:50 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022 Microchip.
*/
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/tee_drv.h>
#define RTC_INFO_VERSION 0x1
#define TA_CMD_RTC_GET_INFO 0x0
#define TA_CMD_RTC_GET_TIME 0x1
#define TA_CMD_RTC_SET_TIME 0x2
#define TA_CMD_RTC_GET_OFFSET 0x3
#define TA_CMD_RTC_SET_OFFSET 0x4
#define TA_RTC_FEATURE_CORRECTION BIT(0)
struct optee_rtc_time {
u32 tm_sec;
u32 tm_min;
u32 tm_hour;
u32 tm_mday;
u32 tm_mon;
u32 tm_year;
u32 tm_wday;
};
struct optee_rtc_info {
u64 version;
u64 features;
struct optee_rtc_time range_min;
struct optee_rtc_time range_max;
};
/**
* struct optee_rtc - OP-TEE RTC private data
* @dev: OP-TEE based RTC device.
* @ctx: OP-TEE context handler.
* @session_id: RTC TA session identifier.
* @shm: Memory pool shared with RTC device.
* @features: Bitfield of RTC features
*/
struct optee_rtc {
struct device *dev;
struct tee_context *ctx;
u32 session_id;
struct tee_shm *shm;
u64 features;
};
static int optee_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
struct tee_ioctl_invoke_arg inv_arg = {0};
struct optee_rtc_time *optee_tm;
struct tee_param param[4] = {0};
int ret;
inv_arg.func = TA_CMD_RTC_GET_TIME;
inv_arg.session = priv->session_id;
inv_arg.num_params = 4;
/* Fill invoke cmd params */
param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
param[0].u.memref.shm = priv->shm;
param[0].u.memref.size = sizeof(struct optee_rtc_time);
ret = tee_client_invoke_func(priv->ctx, &inv_arg, param);
if (ret < 0 || inv_arg.ret != 0)
return ret ? ret : -EPROTO;
optee_tm = tee_shm_get_va(priv->shm, 0);
if (IS_ERR(optee_tm))
return PTR_ERR(optee_tm);
if (param[0].u.memref.size != sizeof(*optee_tm))
return -EPROTO;
tm->tm_sec = optee_tm->tm_sec;
tm->tm_min = optee_tm->tm_min;
tm->tm_hour = optee_tm->tm_hour;
tm->tm_mday = optee_tm->tm_mday;
tm->tm_mon = optee_tm->tm_mon;
tm->tm_year = optee_tm->tm_year - 1900;
tm->tm_wday = optee_tm->tm_wday;
tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
return 0;
}
static int optee_rtc_settime(struct device *dev, struct rtc_time *tm)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
struct tee_ioctl_invoke_arg inv_arg = {0};
struct tee_param param[4] = {0};
struct optee_rtc_time optee_tm;
void *rtc_data;
int ret;
optee_tm.tm_sec = tm->tm_sec;
optee_tm.tm_min = tm->tm_min;
optee_tm.tm_hour = tm->tm_hour;
optee_tm.tm_mday = tm->tm_mday;
optee_tm.tm_mon = tm->tm_mon;
optee_tm.tm_year = tm->tm_year + 1900;
optee_tm.tm_wday = tm->tm_wday;
inv_arg.func = TA_CMD_RTC_SET_TIME;
inv_arg.session = priv->session_id;
inv_arg.num_params = 4;
param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
param[0].u.memref.shm = priv->shm;
param[0].u.memref.size = sizeof(struct optee_rtc_time);
rtc_data = tee_shm_get_va(priv->shm, 0);
if (IS_ERR(rtc_data))
return PTR_ERR(rtc_data);
memcpy(rtc_data, &optee_tm, sizeof(struct optee_rtc_time));
ret = tee_client_invoke_func(priv->ctx, &inv_arg, param);
if (ret < 0 || inv_arg.ret != 0)
return ret ? ret : -EPROTO;
return 0;
}
static int optee_rtc_readoffset(struct device *dev, long *offset)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
struct tee_ioctl_invoke_arg inv_arg = {0};
struct tee_param param[4] = {0};
int ret;
if (!(priv->features & TA_RTC_FEATURE_CORRECTION))
return -EOPNOTSUPP;
inv_arg.func = TA_CMD_RTC_GET_OFFSET;
inv_arg.session = priv->session_id;
inv_arg.num_params = 4;
param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
ret = tee_client_invoke_func(priv->ctx, &inv_arg, param);
if (ret < 0 || inv_arg.ret != 0)
return ret ? ret : -EPROTO;
*offset = param[0].u.value.a;
return 0;
}
static int optee_rtc_setoffset(struct device *dev, long offset)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
struct tee_ioctl_invoke_arg inv_arg = {0};
struct tee_param param[4] = {0};
int ret;
if (!(priv->features & TA_RTC_FEATURE_CORRECTION))
return -EOPNOTSUPP;
inv_arg.func = TA_CMD_RTC_SET_OFFSET;
inv_arg.session = priv->session_id;
inv_arg.num_params = 4;
param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
param[0].u.value.a = offset;
ret = tee_client_invoke_func(priv->ctx, &inv_arg, param);
if (ret < 0 || inv_arg.ret != 0)
return ret ? ret : -EPROTO;
return 0;
}
static const struct rtc_class_ops optee_rtc_ops = {
.read_time = optee_rtc_readtime,
.set_time = optee_rtc_settime,
.set_offset = optee_rtc_setoffset,
.read_offset = optee_rtc_readoffset,
};
static int optee_rtc_read_info(struct device *dev, struct rtc_device *rtc,
u64 *features)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
struct tee_ioctl_invoke_arg inv_arg = {0};
struct tee_param param[4] = {0};
struct optee_rtc_info *info;
struct optee_rtc_time *tm;
int ret;
inv_arg.func = TA_CMD_RTC_GET_INFO;
inv_arg.session = priv->session_id;
inv_arg.num_params = 4;
param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
param[0].u.memref.shm = priv->shm;
param[0].u.memref.size = sizeof(*info);
ret = tee_client_invoke_func(priv->ctx, &inv_arg, param);
if (ret < 0 || inv_arg.ret != 0)
return ret ? ret : -EPROTO;
info = tee_shm_get_va(priv->shm, 0);
if (IS_ERR(info))
return PTR_ERR(info);
if (param[0].u.memref.size != sizeof(*info))
return -EPROTO;
if (info->version != RTC_INFO_VERSION)
return -EPROTO;
*features = info->features;
tm = &info->range_min;
rtc->range_min = mktime64(tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min,
tm->tm_sec);
tm = &info->range_max;
rtc->range_max = mktime64(tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min,
tm->tm_sec);
return 0;
}
static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
{
if (ver->impl_id == TEE_IMPL_ID_OPTEE)
return 1;
else
return 0;
}
static int optee_rtc_probe(struct device *dev)
{
struct tee_client_device *rtc_device = to_tee_client_device(dev);
struct tee_ioctl_open_session_arg sess_arg;
struct optee_rtc *priv;
struct rtc_device *rtc;
struct tee_shm *shm;
int ret, err;
memset(&sess_arg, 0, sizeof(sess_arg));
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
rtc = devm_rtc_allocate_device(dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
/* Open context with TEE driver */
priv->ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
if (IS_ERR(priv->ctx))
return -ENODEV;
/* Open session with rtc Trusted App */
export_uuid(sess_arg.uuid, &rtc_device->id.uuid);
sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
ret = tee_client_open_session(priv->ctx, &sess_arg, NULL);
if (ret < 0 || sess_arg.ret != 0) {
dev_err(dev, "tee_client_open_session failed, err: %x\n", sess_arg.ret);
err = -EINVAL;
goto out_ctx;
}
priv->session_id = sess_arg.session;
shm = tee_shm_alloc_kernel_buf(priv->ctx, sizeof(struct optee_rtc_info));
if (IS_ERR(shm)) {
dev_err(priv->dev, "tee_shm_alloc_kernel_buf failed\n");
err = PTR_ERR(shm);
goto out_sess;
}
priv->shm = shm;
priv->dev = dev;
dev_set_drvdata(dev, priv);
rtc->ops = &optee_rtc_ops;
err = optee_rtc_read_info(dev, rtc, &priv->features);
if (err) {
dev_err(dev, "Failed to get RTC features from OP-TEE\n");
goto out_shm;
}
err = devm_rtc_register_device(rtc);
if (err)
goto out_shm;
/*
* We must clear this bit after registering because rtc_register_device
* will set it if it sees that .set_offset is provided.
*/
if (!(priv->features & TA_RTC_FEATURE_CORRECTION))
clear_bit(RTC_FEATURE_CORRECTION, rtc->features);
return 0;
out_shm:
tee_shm_free(priv->shm);
out_sess:
tee_client_close_session(priv->ctx, priv->session_id);
out_ctx:
tee_client_close_context(priv->ctx);
return err;
}
static int optee_rtc_remove(struct device *dev)
{
struct optee_rtc *priv = dev_get_drvdata(dev);
tee_client_close_session(priv->ctx, priv->session_id);
tee_client_close_context(priv->ctx);
return 0;
}
static const struct tee_client_device_id optee_rtc_id_table[] = {
{UUID_INIT(0xf389f8c8, 0x845f, 0x496c,
0x8b, 0xbe, 0xd6, 0x4b, 0xd2, 0x4c, 0x92, 0xfd)},
{}
};
MODULE_DEVICE_TABLE(tee, optee_rtc_id_table);
static struct tee_client_driver optee_rtc_driver = {
.id_table = optee_rtc_id_table,
.driver = {
.name = "optee_rtc",
.bus = &tee_bus_type,
.probe = optee_rtc_probe,
.remove = optee_rtc_remove,
},
};
static int __init optee_rtc_mod_init(void)
{
return driver_register(&optee_rtc_driver.driver);
}
static void __exit optee_rtc_mod_exit(void)
{
driver_unregister(&optee_rtc_driver.driver);
}
module_init(optee_rtc_mod_init);
module_exit(optee_rtc_mod_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Clément Léger <clement.leger@bootlin.com>");
MODULE_DESCRIPTION("OP-TEE based RTC driver");
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