[v5,3/3] nvmem: stm32: detect bsec pta presence for STM32MP15x
Commit Message
On STM32MP15x SoC, the SMC backend is optional when OP-TEE is used;
the PTA BSEC should be used as it is done on STM32MP13x platform,
but the BSEC SMC can be also used: it is a legacy mode in OP-TEE,
not recommended but used in previous OP-TEE firmware.
The presence of OP-TEE is dynamically detected in STM32MP15x device tree
and the supported NVMEM backend is dynamically detected:
- PTA with stm32_bsec_pta_find
- SMC with stm32_bsec_check
With OP-TEE but without PTA and SMC detection, the probe is deferred for
STM32MP15x devices.
On STM32MP13x platform, only the PTA is supported with cfg->ta = true
and this detection is skipped.
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
---
Changes in v5:
- update the BSEC SMC detection logic in stm32_romem_probe()
after Etienne Carierre review to support NVMEM probe after OP-TEE probe
Changes in v3:
- use of_find_compatible_node in optee_presence_check function
instead of of_find_node_by_path("/firmware/optee")
Changes in v2:
- Added patch in the serie for BSEC PTA support on STM32MP15x
with dynamic detection of OP-TEE presence and SMC support (legacy mode)
drivers/nvmem/stm32-romem.c | 38 +++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
Comments
On Fri, 6 Jan 2023 at 18:04, Patrick Delaunay
<patrick.delaunay@foss.st.com> wrote:
>
> On STM32MP15x SoC, the SMC backend is optional when OP-TEE is used;
> the PTA BSEC should be used as it is done on STM32MP13x platform,
> but the BSEC SMC can be also used: it is a legacy mode in OP-TEE,
> not recommended but used in previous OP-TEE firmware.
>
> The presence of OP-TEE is dynamically detected in STM32MP15x device tree
> and the supported NVMEM backend is dynamically detected:
> - PTA with stm32_bsec_pta_find
> - SMC with stm32_bsec_check
>
> With OP-TEE but without PTA and SMC detection, the probe is deferred for
> STM32MP15x devices.
>
> On STM32MP13x platform, only the PTA is supported with cfg->ta = true
> and this detection is skipped.
>
> Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
> ---
>
> Changes in v5:
> - update the BSEC SMC detection logic in stm32_romem_probe()
> after Etienne Carierre review to support NVMEM probe after OP-TEE probe
>
> Changes in v3:
> - use of_find_compatible_node in optee_presence_check function
> instead of of_find_node_by_path("/firmware/optee")
>
> Changes in v2:
> - Added patch in the serie for BSEC PTA support on STM32MP15x
> with dynamic detection of OP-TEE presence and SMC support (legacy mode)
>
> drivers/nvmem/stm32-romem.c | 38 +++++++++++++++++++++++++++++++++----
> 1 file changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
> index 978a63edf297..e0babc2cebd7 100644
> --- a/drivers/nvmem/stm32-romem.c
> +++ b/drivers/nvmem/stm32-romem.c
> @@ -159,6 +159,31 @@ static int stm32_bsec_pta_write(void *context, unsigned int offset, void *buf,
> return stm32_bsec_optee_ta_write(priv->ctx, priv->lower, offset, buf, bytes);
> }
>
> +static bool stm32_bsec_smc_check(void)
> +{
> + u32 val;
> + int ret;
> +
> + /* check that the OP-TEE support the BSEC SMC (legacy mode) */
> + ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, 0, 0, &val);
> +
> + return !ret;
> +}
> +
> +static bool optee_presence_check(void)
> +{
> + struct device_node *np;
> + bool tee_detected = false;
> +
> + /* check that the OP-TEE node is present and available. */
> + np = of_find_compatible_node(NULL, NULL, "linaro,optee-tz");
> + if (np && of_device_is_available(np))
> + tee_detected = true;
> + of_node_put(np);
> +
> + return tee_detected;
> +}
> +
> static int stm32_romem_probe(struct platform_device *pdev)
> {
> const struct stm32_romem_cfg *cfg;
> @@ -195,11 +220,16 @@ static int stm32_romem_probe(struct platform_device *pdev)
> } else {
> priv->cfg.size = cfg->size;
> priv->lower = cfg->lower;
> - if (cfg->ta) {
> + if (cfg->ta || optee_presence_check()) {
> rc = stm32_bsec_optee_ta_open(&priv->ctx);
> - /* wait for OP-TEE client driver to be up and ready */
> - if (rc)
> - return rc;
> + if (rc) {
> + /* wait for OP-TEE client driver to be up and ready */
> + if (rc == -EPROBE_DEFER)
> + return -EPROBE_DEFER;
> + /* BSEC PTA is required or SMC not ready */
Nitpicking: I would replace "SMC not ready" with "SMC not supported".
Aside that, Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
> + if (cfg->ta || !stm32_bsec_smc_check())
> + return rc;
> + }
> }
> if (priv->ctx) {
> rc = devm_add_action_or_reset(dev, stm32_bsec_optee_ta_close, priv->ctx);
> --
> 2.25.1
>
@@ -159,6 +159,31 @@ static int stm32_bsec_pta_write(void *context, unsigned int offset, void *buf,
return stm32_bsec_optee_ta_write(priv->ctx, priv->lower, offset, buf, bytes);
}
+static bool stm32_bsec_smc_check(void)
+{
+ u32 val;
+ int ret;
+
+ /* check that the OP-TEE support the BSEC SMC (legacy mode) */
+ ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, 0, 0, &val);
+
+ return !ret;
+}
+
+static bool optee_presence_check(void)
+{
+ struct device_node *np;
+ bool tee_detected = false;
+
+ /* check that the OP-TEE node is present and available. */
+ np = of_find_compatible_node(NULL, NULL, "linaro,optee-tz");
+ if (np && of_device_is_available(np))
+ tee_detected = true;
+ of_node_put(np);
+
+ return tee_detected;
+}
+
static int stm32_romem_probe(struct platform_device *pdev)
{
const struct stm32_romem_cfg *cfg;
@@ -195,11 +220,16 @@ static int stm32_romem_probe(struct platform_device *pdev)
} else {
priv->cfg.size = cfg->size;
priv->lower = cfg->lower;
- if (cfg->ta) {
+ if (cfg->ta || optee_presence_check()) {
rc = stm32_bsec_optee_ta_open(&priv->ctx);
- /* wait for OP-TEE client driver to be up and ready */
- if (rc)
- return rc;
+ if (rc) {
+ /* wait for OP-TEE client driver to be up and ready */
+ if (rc == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ /* BSEC PTA is required or SMC not ready */
+ if (cfg->ta || !stm32_bsec_smc_check())
+ return rc;
+ }
}
if (priv->ctx) {
rc = devm_add_action_or_reset(dev, stm32_bsec_optee_ta_close, priv->ctx);