[PATCH] drivers: tee: i2c trampoline driver

Jens Wiklander
2020-12-23T08:12:38Z

Hi Jorge,

On Mon, Dec 21, 2020 at 07:15:40PM +0100, Jorge Ramirez-Ortiz wrote:
> This commit gives the secure world access to the I2C bus so it can
> communicate with I2C slaves (tipically those would be secure elements
> like the NXP SE050).
>
> Tested on imx8mmevk.
>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
> ---
> drivers/tee/optee/Makefile | 1 +
> drivers/tee/optee/i2c.c | 88 ++++++++++++++++++++++++
> drivers/tee/optee/optee_msg.h | 22 ++++++
> drivers/tee/optee/optee_msg_supplicant.h | 5 ++
> drivers/tee/optee/optee_private.h | 12 ++++
> drivers/tee/optee/supplicant.c | 3 +
> 6 files changed, 131 insertions(+)
> create mode 100644 drivers/tee/optee/i2c.c
>
> diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
> index 928d3f8002..068c6e7aa1 100644
> --- a/drivers/tee/optee/Makefile
> +++ b/drivers/tee/optee/Makefile
> @@ -2,4 +2,5 @@
>
> obj-y += core.o
> obj-y += supplicant.o
> +obj-$(CONFIG_DM_I2C) += i2c.o
> obj-$(CONFIG_SUPPORT_EMMC_RPMB) += rpmb.o
> diff --git a/drivers/tee/optee/i2c.c b/drivers/tee/optee/i2c.c
> new file mode 100644
> index 0000000000..2ebbf1ff7c
> --- /dev/null
> +++ b/drivers/tee/optee/i2c.c
> @@ -0,0 +1,88 @@
> +// SPDX-License-Identifier: BSD-2-Clause
> +/*
> + * Copyright (c) 2020 Foundries.io Ltd
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <i2c.h>
> +#include <tee.h>
> +#include "optee_msg.h"
> +#include "optee_private.h"
> +
> +static struct {
> + struct udevice *dev;
> + int chip;
> + int bus;
> +} xfer;
> +
> +void optee_suppl_cmd_i2c_transfer(struct udevice *dev,
> + struct optee_msg_arg *arg)
> +{
> + const uint64_t attr[] = {
A u8 instead of uint64_t would give the same result.

> + OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,
> + OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,
> + OPTEE_MSG_ATTR_TYPE_RMEM_INOUT,
> + OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT,
> + };
> + struct udevice *chip_dev = NULL;
> + struct tee_shm *shm = NULL;
> + uint8_t *buf = NULL;
> + size_t len = 0;
> + int chip = -1;
> + int bus = -1;
> + int ret = -1;
> +
> + if (arg->num_params != ARRAY_SIZE(attr) ||
> + arg->params[0].attr != attr[0] ||
> + arg->params[1].attr != attr[1] ||
> + arg->params[2].attr != attr[2] ||
> + arg->params[3].attr != attr[3]) {
> + arg->ret = TEE_ERROR_BAD_PARAMETERS;
> + return;
> + }
> +
> + len = arg->params[2].u.tmem.size;
> + shm = (struct tee_shm *)(unsigned long)arg->params[2].u.tmem.shm_ref;
Please replace tmem with rmem. The OPTEE_MSG_ATTR_TYPE_RMEM_INOUT above
indicates that we're dealing with a struct optee_msg_param_rmem.

> + buf = shm->addr;
> + if (!buf || !len)
> + goto bad;
> +
> + bus = (int)arg->params[0].u.value.b;
> + chip = (int)arg->params[0].u.value.c;
> +
> + if (!xfer.dev || xfer.chip != chip || xfer.bus != bus) {
> + if (i2c_get_chip_for_busnum(bus, chip, 0, &chip_dev))
> + goto bad;
> +
> + xfer.dev = chip_dev;
> + xfer.chip = chip;
> + xfer.bus = bus;
Is this caching safe? No risk of using stale data?

Thanks,
Jens

> + }
> +
> + if (arg->params[1].u.value.a & OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT)
> + if (i2c_set_chip_flags(xfer.dev, DM_I2C_CHIP_10BIT))
> + goto bad;
> +
> + switch (arg->params[0].u.value.a) {
> + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:
> + ret = dm_i2c_read(xfer.dev, 0, buf, len);
> + break;
> + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:
> + ret = dm_i2c_write(xfer.dev, 0, buf, len);
> + break;
> + default:
> + goto bad;
> + }
> +
> + if (ret) {
> + arg->ret = TEE_ERROR_COMMUNICATION;
> + } else {
> + arg->params[3].u.value.a = len;
> + arg->ret = TEE_SUCCESS;
> + }
> +
> + return;
> +bad:
> + arg->ret = TEE_ERROR_BAD_PARAMETERS;
> +}
> diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
> index 24c60960fc..7cedb59a82 100644
> --- a/drivers/tee/optee/optee_msg.h
> +++ b/drivers/tee/optee/optee_msg.h
> @@ -422,4 +422,26 @@ struct optee_msg_arg {
> */
> #define OPTEE_MSG_RPC_CMD_SHM_FREE 7
>
> +/*
> + * Access a device on an i2c bus
> + *
> + * [in] param[0].u.value.a mode: RD(0), WR(1)
> + * [in] param[0].u.value.b i2c adapter
> + * [in] param[0].u.value.c i2c chip
> + *
> + * [in] param[1].u.value.a i2c control flags
> + * [in] param[1].u.value.b i2c retry (optional)
> + *
> + * [in/out] memref[2] buffer to exchange the transfer data
> + * with the secure world
> + *
> + * [out] param[3].u.value.a bytes transferred by the driver
> + */
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 21
> +/* I2C master transfer modes */
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD 0
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR 1
> +/* I2C master control flags */
> +#define OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT BIT(0)
> +
> #endif /* _OPTEE_MSG_H */
> diff --git a/drivers/tee/optee/optee_msg_supplicant.h b/drivers/tee/optee/optee_msg_supplicant.h
> index a0fb8063c8..963cfd4782 100644
> --- a/drivers/tee/optee/optee_msg_supplicant.h
> +++ b/drivers/tee/optee/optee_msg_supplicant.h
> @@ -147,6 +147,11 @@
> #define OPTEE_MSG_RPC_CMD_SHM_ALLOC 6
> #define OPTEE_MSG_RPC_CMD_SHM_FREE 7
>
> +/*
> + * I2C bus access
> + */
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 21
> +
> /*
> * Was OPTEE_MSG_RPC_CMD_SQL_FS, which isn't supported any longer
> */
> diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
> index 9442d1c176..d7ab1f593f 100644
> --- a/drivers/tee/optee/optee_private.h
> +++ b/drivers/tee/optee/optee_private.h
> @@ -60,6 +60,18 @@ static inline void optee_suppl_rpmb_release(struct udevice *dev)
> }
> #endif
>
> +#ifdef CONFIG_DM_I2C
> +void optee_suppl_cmd_i2c_transfer(struct udevice *dev,
> + struct optee_msg_arg *arg);
> +#else
> +void optee_suppl_cmd_i2c_transfer(struct udevice *dev,
> + struct optee_msg_arg *arg)
> +{
> + debug("OPTEE_MSG_RPC_CMD_I2C_TRANSFER not implemented\n");
> + arg->ret = TEE_ERROR_NOT_IMPLEMENTED;
> +}
> +#endif
> +
> void *optee_alloc_and_init_page_list(void *buf, ulong len, u64 *phys_buf_ptr);
>
> #endif /* __OPTEE_PRIVATE_H */
> diff --git a/drivers/tee/optee/supplicant.c b/drivers/tee/optee/supplicant.c
> index ae042b9a20..f7738983cd 100644
> --- a/drivers/tee/optee/supplicant.c
> +++ b/drivers/tee/optee/supplicant.c
> @@ -89,6 +89,9 @@ void optee_suppl_cmd(struct udevice *dev, struct tee_shm *shm_arg,
> case OPTEE_MSG_RPC_CMD_RPMB:
> optee_suppl_cmd_rpmb(dev, arg);
> break;
> + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER:
> + optee_suppl_cmd_i2c_transfer(dev, arg);
> + break;
> default:
> arg->ret = TEE_ERROR_NOT_IMPLEMENTED;
> }
> --
> 2.17.1
>