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    Subject[RFC PATCH 4/4] remoteproc: stm32: Add support of an OP-TEE TA to load the firmware
    Date
    Add the support of signed firmware using new TEE remoteproc device to
    manage a remote firmware in a secure trusted application.

    The support of a signed or a non signed firmware is based on compatible:
    - with legacy compatible "st,stm32mp1-m4" the Linux kernel loads a
    non-signed (ELF) firmware image,
    - with compatible "st,stm32mp1-m4-tee" the Linux kernel load a signed
    firmware image. In this case it calls TEE services to manage the firmware
    loading and the remoteproc life-cycle.

    Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
    ---
    drivers/remoteproc/Kconfig | 1 +
    drivers/remoteproc/stm32_rproc.c | 234 ++++++++++++++++++++++++++-----
    2 files changed, 198 insertions(+), 37 deletions(-)

    diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
    index 2969f067e3c3..e6f0ca4adf8a 100644
    --- a/drivers/remoteproc/Kconfig
    +++ b/drivers/remoteproc/Kconfig
    @@ -316,6 +316,7 @@ config STM32_RPROC
    depends on ARCH_STM32
    depends on REMOTEPROC
    select MAILBOX
    + select TEE_REMOTEPROC
    help
    Say y here to support STM32 MCU processors via the
    remote processor framework.
    diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
    index 8746cbb1f168..d2c909905cba 100644
    --- a/drivers/remoteproc/stm32_rproc.c
    +++ b/drivers/remoteproc/stm32_rproc.c
    @@ -20,6 +20,7 @@
    #include <linux/remoteproc.h>
    #include <linux/reset.h>
    #include <linux/slab.h>
    +#include <linux/tee_remoteproc.h>
    #include <linux/workqueue.h>

    #include "remoteproc_internal.h"
    @@ -49,6 +50,13 @@
    #define M4_STATE_STANDBY 4
    #define M4_STATE_CRASH 5

    +/*
    + * Define a default index in future may come a global list of
    + * firmwares which list platforms and associated firmware(s)
    + */
    +
    +#define STM32_MP1_FW_ID 0
    +
    struct stm32_syscon {
    struct regmap *map;
    u32 reg;
    @@ -89,6 +97,8 @@ struct stm32_rproc {
    struct stm32_mbox mb[MBOX_NB_MBX];
    struct workqueue_struct *workqueue;
    bool secured_soc;
    + bool fw_loaded;
    + struct tee_rproc *trproc;
    void __iomem *rsc_va;
    };

    @@ -208,6 +218,139 @@ static int stm32_rproc_mbox_idx(struct rproc *rproc, const unsigned char *name)
    return -EINVAL;
    }

    +static void stm32_rproc_request_shutdown(struct rproc *rproc)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    + int err, dummy_data, idx;
    +
    + /* Request shutdown of the remote processor */
    + if (rproc->state != RPROC_OFFLINE && rproc->state != RPROC_CRASHED) {
    + idx = stm32_rproc_mbox_idx(rproc, STM32_MBX_SHUTDOWN);
    + if (idx >= 0 && ddata->mb[idx].chan) {
    + /* A dummy data is sent to allow to block on transmit. */
    + err = mbox_send_message(ddata->mb[idx].chan,
    + &dummy_data);
    + if (err < 0)
    + dev_warn(&rproc->dev, "warning: remote FW shutdown without ack\n");
    + }
    + }
    +}
    +
    +static int stm32_rproc_release(struct rproc *rproc)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    + unsigned int err = 0;
    +
    + /* To allow platform Standby power mode, set remote proc Deep Sleep. */
    + if (ddata->pdds.map) {
    + err = regmap_update_bits(ddata->pdds.map, ddata->pdds.reg,
    + ddata->pdds.mask, 1);
    + if (err) {
    + dev_err(&rproc->dev, "failed to set pdds\n");
    + return err;
    + }
    + }
    +
    + /* Update coprocessor state to OFF if available. */
    + if (ddata->m4_state.map) {
    + err = regmap_update_bits(ddata->m4_state.map,
    + ddata->m4_state.reg,
    + ddata->m4_state.mask,
    + M4_STATE_OFF);
    + if (err) {
    + dev_err(&rproc->dev, "failed to set copro state\n");
    + return err;
    + }
    + }
    +
    + return err;
    +}
    +
    +static int stm32_rproc_tee_elf_sanity_check(struct rproc *rproc,
    + const struct firmware *fw)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    + unsigned int ret = 0;
    +
    + if (rproc->state == RPROC_DETACHED)
    + return 0;
    +
    + ret = tee_rproc_load_fw(ddata->trproc, fw);
    + if (!ret)
    + ddata->fw_loaded = true;
    +
    + return ret;
    +}
    +
    +static int stm32_rproc_tee_elf_load(struct rproc *rproc,
    + const struct firmware *fw)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    + unsigned int ret;
    +
    + /*
    + * This function can be called by remote proc for recovery
    + * without the sanity check. In this case we need to load the firmware
    + * else nothing done here as the firmware has been preloaded for the
    + * sanity check to be able to parse it for the resource table
    + */
    + if (ddata->fw_loaded)
    + return 0;
    +
    + ret = tee_rproc_load_fw(ddata->trproc, fw);
    + if (ret)
    + return ret;
    + ddata->fw_loaded = true;
    +
    + /* update the resource table parameters */
    + if (rproc_tee_get_rsc_table(ddata->trproc)) {
    + /* no resource table: reset the related fields */
    + rproc->cached_table = NULL;
    + rproc->table_ptr = NULL;
    + rproc->table_sz = 0;
    + }
    +
    + return 0;
    +}
    +
    +static struct resource_table *
    +stm32_rproc_tee_elf_find_loaded_rsc_table(struct rproc *rproc,
    + const struct firmware *fw)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    +
    + return tee_rproc_get_loaded_rsc_table(ddata->trproc);
    +}
    +
    +static int stm32_rproc_tee_start(struct rproc *rproc)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    +
    + return tee_rproc_start(ddata->trproc);
    +}
    +
    +static int stm32_rproc_tee_attach(struct rproc *rproc)
    +{
    + /* Nothing to do, remote proc already started by the secured context */
    + return 0;
    +}
    +
    +static int stm32_rproc_tee_stop(struct rproc *rproc)
    +{
    + struct stm32_rproc *ddata = rproc->priv;
    + int err;
    +
    + stm32_rproc_request_shutdown(rproc);
    +
    + err = tee_rproc_stop(ddata->trproc);
    + if (err)
    + return err;
    +
    + ddata->fw_loaded = false;
    +
    + return stm32_rproc_release(rproc);
    +}
    +
    static int stm32_rproc_prepare(struct rproc *rproc)
    {
    struct device *dev = rproc->dev.parent;
    @@ -270,7 +413,14 @@ static int stm32_rproc_prepare(struct rproc *rproc)

    static int stm32_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
    {
    - if (rproc_elf_load_rsc_table(rproc, fw))
    + struct stm32_rproc *ddata = rproc->priv;
    + int ret;
    +
    + if (ddata->trproc)
    + ret = rproc_tee_get_rsc_table(ddata->trproc);
    + else
    + ret = rproc_elf_load_rsc_table(rproc, fw);
    + if (ret)
    dev_warn(&rproc->dev, "no resource table found for this firmware\n");

    return 0;
    @@ -503,17 +653,9 @@ static int stm32_rproc_detach(struct rproc *rproc)
    static int stm32_rproc_stop(struct rproc *rproc)
    {
    struct stm32_rproc *ddata = rproc->priv;
    - int err, idx;
    + int err;

    - /* request shutdown of the remote processor */
    - if (rproc->state != RPROC_OFFLINE && rproc->state != RPROC_CRASHED) {
    - idx = stm32_rproc_mbox_idx(rproc, STM32_MBX_SHUTDOWN);
    - if (idx >= 0 && ddata->mb[idx].chan) {
    - err = mbox_send_message(ddata->mb[idx].chan, "detach");
    - if (err < 0)
    - dev_warn(&rproc->dev, "warning: remote FW shutdown without ack\n");
    - }
    - }
    + stm32_rproc_request_shutdown(rproc);

    err = stm32_rproc_set_hold_boot(rproc, true);
    if (err)
    @@ -525,29 +667,8 @@ static int stm32_rproc_stop(struct rproc *rproc)
    return err;
    }

    - /* to allow platform Standby power mode, set remote proc Deep Sleep */
    - if (ddata->pdds.map) {
    - err = regmap_update_bits(ddata->pdds.map, ddata->pdds.reg,
    - ddata->pdds.mask, 1);
    - if (err) {
    - dev_err(&rproc->dev, "failed to set pdds\n");
    - return err;
    - }
    - }
    -
    - /* update coprocessor state to OFF if available */
    - if (ddata->m4_state.map) {
    - err = regmap_update_bits(ddata->m4_state.map,
    - ddata->m4_state.reg,
    - ddata->m4_state.mask,
    - M4_STATE_OFF);
    - if (err) {
    - dev_err(&rproc->dev, "failed to set copro state\n");
    - return err;
    - }
    - }

    - return 0;
    + return stm32_rproc_release(rproc);
    }

    static void stm32_rproc_kick(struct rproc *rproc, int vqid)
    @@ -659,8 +780,22 @@ static const struct rproc_ops st_rproc_ops = {
    .get_boot_addr = rproc_elf_get_boot_addr,
    };

    +static const struct rproc_ops st_rproc_tee_ops = {
    + .prepare = stm32_rproc_prepare,
    + .start = stm32_rproc_tee_start,
    + .stop = stm32_rproc_tee_stop,
    + .attach = stm32_rproc_tee_attach,
    + .kick = stm32_rproc_kick,
    + .parse_fw = stm32_rproc_parse_fw,
    + .find_loaded_rsc_table = stm32_rproc_tee_elf_find_loaded_rsc_table,
    + .get_loaded_rsc_table = stm32_rproc_get_loaded_rsc_table,
    + .sanity_check = stm32_rproc_tee_elf_sanity_check,
    + .load = stm32_rproc_tee_elf_load,
    +};
    +
    static const struct of_device_id stm32_rproc_match[] = {
    - { .compatible = "st,stm32mp1-m4" },
    + {.compatible = "st,stm32mp1-m4",},
    + {.compatible = "st,stm32mp1-m4-tee",},
    {},
    };
    MODULE_DEVICE_TABLE(of, stm32_rproc_match);
    @@ -801,6 +936,7 @@ static int stm32_rproc_probe(struct platform_device *pdev)
    struct device *dev = &pdev->dev;
    struct stm32_rproc *ddata;
    struct device_node *np = dev->of_node;
    + struct tee_rproc *trproc;
    struct rproc *rproc;
    unsigned int state;
    int ret;
    @@ -809,11 +945,29 @@ static int stm32_rproc_probe(struct platform_device *pdev)
    if (ret)
    return ret;

    - rproc = rproc_alloc(dev, np->name, &st_rproc_ops, NULL, sizeof(*ddata));
    - if (!rproc)
    - return -ENOMEM;
    + if (of_device_is_compatible(np, "st,stm32mp1-m4-tee")) {
    + trproc = tee_rproc_register(dev, STM32_MP1_FW_ID);
    + if (IS_ERR_OR_NULL(trproc)) {
    + return PTR_ERR(trproc);
    + /*
    + * Delegate the firmware management to the secure context.
    + * The firmware loaded has to be signed.
    + */
    + dev_info(dev, "Support of signed firmware only\n");
    + }
    + }
    + rproc = rproc_alloc(dev, np->name,
    + trproc ? &st_rproc_tee_ops : &st_rproc_ops,
    + NULL, sizeof(*ddata));
    + if (!rproc) {
    + ret = -ENOMEM;
    + goto free_tee;
    + }

    ddata = rproc->priv;
    + ddata->trproc = trproc;
    + if (trproc)
    + ddata->trproc->rproc = rproc;

    rproc_coredump_set_elf_info(rproc, ELFCLASS32, EM_NONE);

    @@ -864,6 +1018,10 @@ static int stm32_rproc_probe(struct platform_device *pdev)
    device_init_wakeup(dev, false);
    }
    rproc_free(rproc);
    +free_tee:
    + if (trproc)
    + tee_rproc_unregister(trproc);
    +
    return ret;
    }

    @@ -885,6 +1043,8 @@ static int stm32_rproc_remove(struct platform_device *pdev)
    device_init_wakeup(dev, false);
    }
    rproc_free(rproc);
    + if (ddata->trproc)
    + tee_rproc_unregister(ddata->trproc);

    return 0;
    }
    --
    2.25.1
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