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Subject[PATCH v4] rtc: optee: add RTC driver for OP-TEE RTC PTA
Date
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>
---

Changes in v4:
- Remove error prints except the ones in probe

Changes in v3 (was resent as a second v2 due to a mistake);
- Fix error messages to include ret value and fix wrong IOCTL names
- Use 100 columns char limit

Changes in v2:
- Rebased over tee-shm-for-v5.18
- Switch to tee_shm_alloc_kernel_buf()
- Use export_uuid() to copy uuid
- Fix warnings reported by checkpatch
- Free SHM in error exit path

MAINTAINERS | 6 +
drivers/rtc/Kconfig | 10 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-optee.c | 362 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 379 insertions(+)
create mode 100644 drivers/rtc/rtc-optee.c

diff --git a/MAINTAINERS b/MAINTAINERS
index f41088418aae..b21375ad73d2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14361,6 +14361,12 @@ L: op-tee@lists.trustedfirmware.org
S: Maintained
F: drivers/char/hw_random/optee-rng.c

+OP-TEE RTC DRIVER
+M: Clément Léger <clement.leger@bootlin.com>
+L: linux-rtc@vger.kernel.org
+S: Maintained
+F: drivers/rtc/rtc-optee.c
+
OPA-VNIC DRIVER
M: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
M: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d85a3c31347c..cba5427f79b3 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1293,6 +1293,16 @@ config RTC_DRV_OPAL
This driver can also be built as a module. If so, the module
will be called rtc-opal.

+config RTC_DRV_OPTEE
+ tristate "OP-TEE based RTC driver"
+ depends on OPTEE
+ help
+ Select this to get support for OP-TEE based RTC control on SoCs where
+ RTC are not accessible to the normal world (Linux).
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-optee.
+
config RTC_DRV_ZYNQMP
tristate "Xilinx Zynq Ultrascale+ MPSoC RTC"
depends on OF && HAS_IOMEM
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index e92f3e943245..2d827d8261d5 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -115,6 +115,7 @@ obj-$(CONFIG_RTC_DRV_GAMECUBE) += rtc-gamecube.o
obj-$(CONFIG_RTC_DRV_NTXEC) += rtc-ntxec.o
obj-$(CONFIG_RTC_DRV_OMAP) += rtc-omap.o
obj-$(CONFIG_RTC_DRV_OPAL) += rtc-opal.o
+obj-$(CONFIG_RTC_DRV_OPTEE) += rtc-optee.o
obj-$(CONFIG_RTC_DRV_PALMAS) += rtc-palmas.o
obj-$(CONFIG_RTC_DRV_PCAP) += rtc-pcap.o
obj-$(CONFIG_RTC_DRV_PCF2123) += rtc-pcf2123.o
diff --git a/drivers/rtc/rtc-optee.c b/drivers/rtc/rtc-optee.c
new file mode 100644
index 000000000000..9f8b5d4a8f6b
--- /dev/null
+++ b/drivers/rtc/rtc-optee.c
@@ -0,0 +1,362 @@
+// 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");
--
2.34.1
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