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Message-ID: <20200812114705.GA16922@trex>
Date: Wed, 12 Aug 2020 13:47:05 +0200
From: "Jorge Ramirez-Ortiz, Foundries" <jorge@...ndries.io>
To: Jens Wiklander <jens.wiklander@...aro.org>
Cc: Jorge Ramirez-Ortiz <jorge@...ndries.io>, sumit.garg@...aro.org,
ricardo@...ndries.io, mike@...ndries.io, tee-dev@...ts.linaro.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCHv7] drivers: optee: allow op-tee to access devices on the
i2c bus
On 12/08/20, Jens Wiklander wrote:
> On Tue, Aug 11, 2020 at 07:55:31PM +0200, Jorge Ramirez-Ortiz wrote:
> > Some secure elements like NXP's SE050 sit on I2C buses. For OP-TEE to
> > control this type of cryptographic devices it needs coordinated access
> > to the bus, so collisions and RUNTIME_PM dont get in the way.
> >
> > This trampoline driver allow OP-TEE to access them.
> >
> > Signed-off-by: Jorge Ramirez-Ortiz <jorge@...ndries.io>
> > ---
> > v7: add support for ten bit i2c slave addressing
> > v6: compile out if CONFIG_I2C not enabled
> > v5: alphabetic order of includes
> > v4: remove unnecessary extra line in optee_msg.h
> > v3: use from/to msg param to support all types of memory
> > modify OPTEE_MSG_RPC_CMD_I2C_TRANSFER message id
> >
> > drivers/tee/optee/optee_msg.h | 21 ++++++++
> > drivers/tee/optee/rpc.c | 95 +++++++++++++++++++++++++++++++++++
> > 2 files changed, 116 insertions(+)
> >
> > diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
> > index 795bc19ae17a..7b2d919da2ac 100644
> > --- a/drivers/tee/optee/optee_msg.h
> > +++ b/drivers/tee/optee/optee_msg.h
> > @@ -419,4 +419,25 @@ 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/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/rpc.c b/drivers/tee/optee/rpc.c
> > index b4ade54d1f28..b6178761d79f 100644
> > --- a/drivers/tee/optee/rpc.c
> > +++ b/drivers/tee/optee/rpc.c
> > @@ -7,6 +7,7 @@
> >
> > #include <linux/delay.h>
> > #include <linux/device.h>
> > +#include <linux/i2c.h>
> > #include <linux/slab.h>
> > #include <linux/tee_drv.h>
> > #include "optee_private.h"
> > @@ -49,6 +50,97 @@ static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg)
> > arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> > }
> >
> > +#if IS_ENABLED(CONFIG_I2C)
> > +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> > + struct optee_msg_arg *arg)
> > +{
> > + struct i2c_client client = { 0 };
> > + struct tee_param *params;
> > + int i, ret = -EOPNOTSUPP;
> > + uint32_t attr[] = {
> uint32_t seems a randomly chosen type here. The
> TEE_IOCTL_PARAM_ATTR_TYPE_* defines fit in a u8.
> Consider u8 attr[] = { instead.
ok
>
> > + TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> > + TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> > + TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
> > + TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT,
> > + };
> > +
> > + if (arg->num_params != ARRAY_SIZE(attr)) {
> > + arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> > + return;
> > + }
> > +
> > + params = kmalloc_array(arg->num_params, sizeof(struct tee_param),
> > + GFP_KERNEL);
> > + if (!params) {
> > + arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
> > + return;
> > + }
> > +
> > + if (optee_from_msg_param(params, arg->num_params, arg->params))
> > + goto bad;
> > +
> > + for (i = 0; i < arg->num_params; i++) {
> arg->num_params has an unsigned type. Consider giving i an unsigned type
> too.
ok
>
> > + if ((params[i].attr & TEE_IOCTL_PARAM_ATTR_TYPE_MASK)
> > + != attr[i])
> It looks a bit funny with the comparison at the beginning of the line,
> normally we try to leave those at the end of the line. But
> optee_from_msg_param() doesn't set any higher bits in params[i].attr so
> you could also simplify the expression as:
> if (params[i].attr != attr[i])
ok will do the above
>
> > + goto bad;
> > + }
> > +
> > + client.adapter = i2c_get_adapter(params[0].u.value.b);
> > + if (!client.adapter)
> > + goto bad;
> > +
> > + if (params[1].u.value.a & OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT) {
> > + if (!i2c_check_functionality(client.adapter,
> > + I2C_FUNC_10BIT_ADDR)) {
> > + i2c_put_adapter(client.adapter);
> > + goto bad;
> > + }
> > +
> > + client.flags = I2C_CLIENT_TEN;
> > + }
> > +
> > + client.addr = params[0].u.value.c;
> > + snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);
> > +
> > + switch (params[0].u.value.a) {
> > + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:
> > + ret = i2c_master_recv(&client, params[2].u.memref.shm->kaddr,
> > + params[2].u.memref.size);
> > + break;
> > + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:
> > + ret = i2c_master_send(&client, params[2].u.memref.shm->kaddr,
> > + params[2].u.memref.size);
> > + break;
> > + default:
> > + i2c_put_adapter(client.adapter);
> > + goto bad;
> > + }
> > +
> > + if (ret < 0) {
> > + arg->ret = TEEC_ERROR_COMMUNICATION;
> > + } else {
> > + params[3].u.value.a = ret;
> > + arg->ret = TEEC_SUCCESS;
> > +
> > + if (optee_to_msg_param(arg->params, arg->num_params, params))
> > + arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> Need
> arg->ret = TEEC_SUCCESS;
> when everything is OK.
it is already there.
but will do an else so it is more evident
>
> > + }
> > +
> > + i2c_put_adapter(client.adapter);
> > + kfree(params);
> > + return;
> > +bad:
> > + kfree(params);
> > + arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> > +}
> > +#else
> > +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> > + struct optee_msg_arg *arg)
> > +{
> > + arg->ret = TEEC_ERROR_COMMUNICATION;
> I'd prefer TEEC_ERROR_NOT_SUPPORTED here.
> TEEC_ERROR_NOT_SUPPORTED would need to be defined as:
> #define TEEC_ERROR_NOT_SUPPORTED 0xFFFF000A
> in optee_private.h
ok
thanks for the quick review on this
>
> Cheers,
> Jens
>
> > +}
> > +#endif
> > +
> > static struct wq_entry *wq_entry_get(struct optee_wait_queue *wq, u32 key)
> > {
> > struct wq_entry *w;
> > @@ -382,6 +474,9 @@ static void handle_rpc_func_cmd(struct tee_context *ctx, struct optee *optee,
> > case OPTEE_MSG_RPC_CMD_SHM_FREE:
> > handle_rpc_func_cmd_shm_free(ctx, arg);
> > break;
> > + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER:
> > + handle_rpc_func_cmd_i2c_transfer(ctx, arg);
> > + break;
> > default:
> > handle_rpc_supp_cmd(ctx, arg);
> > }
> > --
> > 2.17.1
> >
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