Commit df2f34ef authored by Patrick Delaunay's avatar Patrick Delaunay Committed by Greg Kroah-Hartman
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nvmem: stm32: detect bsec pta presence for STM32MP15x 



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: default avatarPatrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: default avatarEtienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230206134356.839737-19-srinivas.kandagatla@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6a0bc352

drivers/nvmem/stm32-romem.c

+34 −4
Original line number Diff line number Diff line
@@ -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;
@@ -195,12 +220,17 @@ 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);

			if (rc) {

				/* wait for OP-TEE client driver to be up and ready */

			if (rc)

				if (rc == -EPROBE_DEFER)

					return -EPROBE_DEFER;

				/* BSEC PTA is required or SMC not supported */

				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);

			if (rc) {