target/linux/generic/backport-6.1/809-v6.3-0008-nvmem-stm32-detect-bsec-pta-presence-for-STM32MP15x.patch

   1 From df2f34ef1d924125ffaf29dfdaf7cdbd3183c321 Mon Sep 17 00:00:00 2001
   2 From: Patrick Delaunay <patrick.delaunay@foss.st.com>
   3 Date: Mon, 6 Feb 2023 13:43:52 +0000
   4 Subject: [PATCH] nvmem: stm32: detect bsec pta presence for STM32MP15x
   5
   6 On STM32MP15x SoC, the SMC backend is optional when OP-TEE is used;
   7 the PTA BSEC should be used as it is done on STM32MP13x platform,
   8 but the BSEC SMC can be also used: it is a legacy mode in OP-TEE,
   9 not recommended but used in previous OP-TEE firmware.
  10
  11 The presence of OP-TEE is dynamically detected in STM32MP15x device tree
  12 and the supported NVMEM backend is dynamically detected:
  13 - PTA with stm32_bsec_pta_find
  14 - SMC with stm32_bsec_check
  15
  16 With OP-TEE but without PTA and SMC detection, the probe is deferred for
  17 STM32MP15x devices.
  18
  19 On STM32MP13x platform, only the PTA is supported with cfg->ta = true
  20 and this detection is skipped.
  21
  22 Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
  23 Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
  24 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  25 Link: https://lore.kernel.org/r/20230206134356.839737-19-srinivas.kandagatla@linaro.org
  26 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  27 ---
  28  drivers/nvmem/stm32-romem.c | 38 +++++++++++++++++++++++++++++++++----
  29  1 file changed, 34 insertions(+), 4 deletions(-)
  30
  31 --- a/drivers/nvmem/stm32-romem.c
  32 +++ b/drivers/nvmem/stm32-romem.c
  33 @@ -159,6 +159,31 @@ static int stm32_bsec_pta_write(void *co
  34         return stm32_bsec_optee_ta_write(priv->ctx, priv->lower, offset, buf, bytes);
  35  }
  36
  37 +static bool stm32_bsec_smc_check(void)
  38 +{
  39 +       u32 val;
  40 +       int ret;
  41 +
  42 +       /* check that the OP-TEE support the BSEC SMC (legacy mode) */
  43 +       ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, 0, 0, &val);
  44 +
  45 +       return !ret;
  46 +}
  47 +
  48 +static bool optee_presence_check(void)
  49 +{
  50 +       struct device_node *np;
  51 +       bool tee_detected = false;
  52 +
  53 +       /* check that the OP-TEE node is present and available. */
  54 +       np = of_find_compatible_node(NULL, NULL, "linaro,optee-tz");
  55 +       if (np && of_device_is_available(np))
  56 +               tee_detected = true;
  57 +       of_node_put(np);
  58 +
  59 +       return tee_detected;
  60 +}
  61 +
  62  static int stm32_romem_probe(struct platform_device *pdev)
  63  {
  64         const struct stm32_romem_cfg *cfg;
  65 @@ -195,11 +220,16 @@ static int stm32_romem_probe(struct plat
  66         } else {
  67                 priv->cfg.size = cfg->size;
  68                 priv->lower = cfg->lower;
  69 -               if (cfg->ta) {
  70 +               if (cfg->ta || optee_presence_check()) {
  71                         rc = stm32_bsec_optee_ta_open(&priv->ctx);
  72 -                       /* wait for OP-TEE client driver to be up and ready */
  73 -                       if (rc)
  74 -                               return rc;
  75 +                       if (rc) {
  76 +                               /* wait for OP-TEE client driver to be up and ready */
  77 +                               if (rc == -EPROBE_DEFER)
  78 +                                       return -EPROBE_DEFER;
  79 +                               /* BSEC PTA is required or SMC not supported */
  80 +                               if (cfg->ta || !stm32_bsec_smc_check())
  81 +                                       return rc;
  82 +                       }
  83                 }
  84                 if (priv->ctx) {
  85                         rc = devm_add_action_or_reset(dev, stm32_bsec_optee_ta_close, priv->ctx);