EDAC/bluefield: Use Arm SMC for EMI access on BlueField-2

The BlueField EDAC driver supports the first generation BlueField-1 SoC, but
not the second generation BlueField-2 SoC. The BlueField-2 SoC is different in
that only secure accesses are allowed to the External Memory Interface (EMI)
register block. On BlueField-2, all read/write accesses from Linux to EMI
registers are routed via the Arm Secure Monitor Call (SMC) through Arm Trusted
Firmware (ATF), which runs at EL3 privileged state.

On BlueField-1, EMI registers are mapped and accessed directly. In order to
support BlueField-2, the driver's read and write access methods must be
extended with additional logic to include secure access to the EMI registers
via SMCs.

  [ bp: Move struct member comments above them, simplify. ]

Signed-off-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shravan Kumar Ramani <shravankr@nvidia.com>
Link: https://lore.kernel.org/r/20241021233013.18405-1-davthompson@nvidia.com

drivers/edac/bluefield_edac.c

@@ -47,13 +47,22 @@
 #define MLXBF_EDAC_MAX_DIMM_PER_MC	2
 #define MLXBF_EDAC_ERROR_GRAIN		8
 
+#define MLXBF_WRITE_REG_32		(0x82000009)
+#define MLXBF_READ_REG_32		(0x8200000A)
+#define MLXBF_SIP_SVC_VERSION		(0x8200ff03)
+
+#define MLXBF_SMCCC_ACCESS_VIOLATION	(-4)
+
+#define MLXBF_SVC_REQ_MAJOR		0
+#define MLXBF_SVC_REQ_MINOR		3
+
 /*
- * Request MLNX_SIP_GET_DIMM_INFO
+ * Request MLXBF_SIP_GET_DIMM_INFO
  *
  * Retrieve information about DIMM on a certain slot.
  *
  * Call register usage:
- * a0: MLNX_SIP_GET_DIMM_INFO
+ * a0: MLXBF_SIP_GET_DIMM_INFO
  * a1: (Memory controller index) << 16 | (Dimm index in memory controller)
  * a2-7: not used.
  *
@@ -61,7 +70,7 @@
  * a0: MLXBF_DIMM_INFO defined below describing the DIMM.
  * a1-3: not used.
  */
-#define MLNX_SIP_GET_DIMM_INFO		0x82000008
+#define MLXBF_SIP_GET_DIMM_INFO		0x82000008
 
 /* Format for the SMC response about the memory information */
 #define MLXBF_DIMM_INFO__SIZE_GB GENMASK_ULL(15, 0)
@@ -72,9 +81,15 @@
 #define MLXBF_DIMM_INFO__PACKAGE_X GENMASK_ULL(31, 24)
 
 struct bluefield_edac_priv {
+	/* pointer to device structure */
+	struct device *dev;
 	int dimm_ranks[MLXBF_EDAC_MAX_DIMM_PER_MC];
 	void __iomem *emi_base;
 	int dimm_per_mc;
+	/* access to secure regs supported */
+	bool svc_sreg_support;
+	/* SMC table# for secure regs access */
+	u32 sreg_tbl;
 };
 
 static u64 smc_call1(u64 smc_op, u64 smc_arg)
@@ -86,6 +101,71 @@ static u64 smc_call1(u64 smc_op, u64 smc_arg)
 	return res.a0;
 }
 
+static int secure_readl(void __iomem *addr, u32 *result, u32 sreg_tbl)
+{
+	struct arm_smccc_res res;
+	int status;
+
+	arm_smccc_smc(MLXBF_READ_REG_32, sreg_tbl, (uintptr_t)addr,
+		      0, 0, 0, 0, 0, &res);
+
+	status = res.a0;
+
+	if (status == SMCCC_RET_NOT_SUPPORTED ||
+	    status == MLXBF_SMCCC_ACCESS_VIOLATION)
+		return -1;
+
+	*result = (u32)res.a1;
+	return 0;
+}
+
+static int secure_writel(void __iomem *addr, u32 data, u32 sreg_tbl)
+{
+	struct arm_smccc_res res;
+	int status;
+
+	arm_smccc_smc(MLXBF_WRITE_REG_32, sreg_tbl, data, (uintptr_t)addr,
+		      0, 0, 0, 0, &res);
+
+	status = res.a0;
+
+	if (status == SMCCC_RET_NOT_SUPPORTED ||
+	    status == MLXBF_SMCCC_ACCESS_VIOLATION)
+		return -1;
+	else
+		return 0;
+}
+
+static int bluefield_edac_readl(struct bluefield_edac_priv *priv, u32 offset, u32 *result)
+{
+	void __iomem *addr;
+	int err = 0;
+
+	addr = priv->emi_base + offset;
+
+	if (priv->svc_sreg_support)
+		err = secure_readl(addr, result, priv->sreg_tbl);
+	else
+		*result = readl(addr);
+
+	return err;
+}
+
+static int bluefield_edac_writel(struct bluefield_edac_priv *priv, u32 offset, u32 data)
+{
+	void __iomem *addr;
+	int err = 0;
+
+	addr = priv->emi_base + offset;
+
+	if (priv->svc_sreg_support)
+		err = secure_writel(addr, data, priv->sreg_tbl);
+	else
+		writel(data, addr);
+
+	return err;
+}
+
 /*
  * Gather the ECC information from the External Memory Interface registers
  * and report it to the edac handler.
@@ -99,7 +179,7 @@ static void bluefield_gather_report_ecc(struct mem_ctl_info *mci,
 	u32 ecc_latch_select, dram_syndrom, serr, derr, syndrom;
 	enum hw_event_mc_err_type ecc_type;
 	u64 ecc_dimm_addr;
-	int ecc_dimm;
+	int ecc_dimm, err;
 
 	ecc_type = is_single_ecc ? HW_EVENT_ERR_CORRECTED :
 				   HW_EVENT_ERR_UNCORRECTED;
@@ -109,14 +189,19 @@ static void bluefield_gather_report_ecc(struct mem_ctl_info *mci,
 	 * registers with information about the last ECC error occurrence.
 	 */
 	ecc_latch_select = MLXBF_ECC_LATCH_SEL__START;
-	writel(ecc_latch_select, priv->emi_base + MLXBF_ECC_LATCH_SEL);
+	err = bluefield_edac_writel(priv, MLXBF_ECC_LATCH_SEL, ecc_latch_select);
+	if (err)
+		dev_err(priv->dev, "ECC latch select write failed.\n");
 
 	/*
 	 * Verify that the ECC reported info in the registers is of the
 	 * same type as the one asked to report. If not, just report the
 	 * error without the detailed information.
 	 */
-	dram_syndrom = readl(priv->emi_base + MLXBF_SYNDROM);
+	err = bluefield_edac_readl(priv, MLXBF_SYNDROM, &dram_syndrom);
+	if (err)
+		dev_err(priv->dev, "DRAM syndrom read failed.\n");
+
 	serr = FIELD_GET(MLXBF_SYNDROM__SERR, dram_syndrom);
 	derr = FIELD_GET(MLXBF_SYNDROM__DERR, dram_syndrom);
 	syndrom = FIELD_GET(MLXBF_SYNDROM__SYN, dram_syndrom);
@@ -127,13 +212,21 @@ static void bluefield_gather_report_ecc(struct mem_ctl_info *mci,
 		return;
 	}
 
-	dram_additional_info = readl(priv->emi_base + MLXBF_ADD_INFO);
+	err = bluefield_edac_readl(priv, MLXBF_ADD_INFO, &dram_additional_info);
+	if (err)
+		dev_err(priv->dev, "DRAM additional info read failed.\n");
+
 	err_prank = FIELD_GET(MLXBF_ADD_INFO__ERR_PRANK, dram_additional_info);
 
 	ecc_dimm = (err_prank >= 2 && priv->dimm_ranks[0] <= 2) ? 1 : 0;
 
-	edea0 = readl(priv->emi_base + MLXBF_ERR_ADDR_0);
+	err = bluefield_edac_readl(priv, MLXBF_ERR_ADDR_0, &edea0);
-	edea1 = readl(priv->emi_base + MLXBF_ERR_ADDR_1);
+	if (err)
+		dev_err(priv->dev, "Error addr 0 read failed.\n");
+
+	err = bluefield_edac_readl(priv, MLXBF_ERR_ADDR_1, &edea1);
+	if (err)
+		dev_err(priv->dev, "Error addr 1 read failed.\n");
 
 	ecc_dimm_addr = ((u64)edea1 << 32) | edea0;
 
@@ -147,6 +240,7 @@ static void bluefield_edac_check(struct mem_ctl_info *mci)
 {
 	struct bluefield_edac_priv *priv = mci->pvt_info;
 	u32 ecc_count, single_error_count, double_error_count, ecc_error = 0;
+	int err;
 
 	/*
 	 * The memory controller might not be initialized by the firmware
@@ -155,7 +249,10 @@ static void bluefield_edac_check(struct mem_ctl_info *mci)
 	if (mci->edac_cap == EDAC_FLAG_NONE)
 		return;
 
-	ecc_count = readl(priv->emi_base + MLXBF_ECC_CNT);
+	err = bluefield_edac_readl(priv, MLXBF_ECC_CNT, &ecc_count);
+	if (err)
+		dev_err(priv->dev, "ECC count read failed.\n");
+
 	single_error_count = FIELD_GET(MLXBF_ECC_CNT__SERR_CNT, ecc_count);
 	double_error_count = FIELD_GET(MLXBF_ECC_CNT__DERR_CNT, ecc_count);
 
@@ -172,8 +269,11 @@ static void bluefield_edac_check(struct mem_ctl_info *mci)
 	}
 
 	/* Write to clear reported errors. */
-	if (ecc_count)
+	if (ecc_count) {
-		writel(ecc_error, priv->emi_base + MLXBF_ECC_ERR);
+		err = bluefield_edac_writel(priv, MLXBF_ECC_ERR, ecc_error);
+		if (err)
+			dev_err(priv->dev, "ECC Error write failed.\n");
+	}
 }
 
 /* Initialize the DIMMs information for the given memory controller. */
@@ -189,7 +289,7 @@ static void bluefield_edac_init_dimms(struct mem_ctl_info *mci)
 		dimm = mci->dimms[i];
 
 		smc_arg = mem_ctrl_idx << 16 | i;
-		smc_info = smc_call1(MLNX_SIP_GET_DIMM_INFO, smc_arg);
+		smc_info = smc_call1(MLXBF_SIP_GET_DIMM_INFO, smc_arg);
 
 		if (!FIELD_GET(MLXBF_DIMM_INFO__SIZE_GB, smc_info)) {
 			dimm->mtype = MEM_EMPTY;
@@ -244,6 +344,7 @@ static int bluefield_edac_mc_probe(struct platform_device *pdev)
 	struct bluefield_edac_priv *priv;
 	struct device *dev = &pdev->dev;
 	struct edac_mc_layer layers[1];
+	struct arm_smccc_res res;
 	struct mem_ctl_info *mci;
 	struct resource *emi_res;
 	unsigned int mc_idx, dimm_count;
@@ -279,13 +380,43 @@ static int bluefield_edac_mc_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	priv = mci->pvt_info;
+	priv->dev = dev;
+
+	/*
+	 * The "sec_reg_block" property in the ACPI table determines the method
+	 * the driver uses to access the EMI registers:
+	 * a) property is not present - directly access registers via readl/writel
+	 * b) property is present - indirectly access registers via SMC calls
+	 *    (assuming required Silicon Provider service version found)
+	 */
+	if (device_property_read_u32(dev, "sec_reg_block", &priv->sreg_tbl)) {
+		priv->svc_sreg_support = false;
+	} else {
+		/*
+		 * Check for minimum required Arm Silicon Provider (SiP) service
+		 * version, ensuring support of required SMC function IDs.
+		 */
+		arm_smccc_smc(MLXBF_SIP_SVC_VERSION, 0, 0, 0, 0, 0, 0, 0, &res);
+		if (res.a0 == MLXBF_SVC_REQ_MAJOR &&
+		    res.a1 >= MLXBF_SVC_REQ_MINOR) {
+			priv->svc_sreg_support = true;
+		} else {
+			dev_err(dev, "Required SMCs are not supported.\n");
+			ret = -EINVAL;
+			goto err;
+		}
+	}
 
 	priv->dimm_per_mc = dimm_count;
-	priv->emi_base = devm_ioremap_resource(dev, emi_res);
+	if (!priv->svc_sreg_support) {
-	if (IS_ERR(priv->emi_base)) {
+		priv->emi_base = devm_ioremap_resource(dev, emi_res);
-		dev_err(dev, "failed to map EMI IO resource\n");
+		if (IS_ERR(priv->emi_base)) {
-		ret = PTR_ERR(priv->emi_base);
+			dev_err(dev, "failed to map EMI IO resource\n");
-		goto err;
+			ret = PTR_ERR(priv->emi_base);
+			goto err;
+		}
+	} else {
+		priv->emi_base = (void __iomem *)emi_res->start;
 	}
 
 	mci->pdev = dev;
@@ -320,7 +451,6 @@ static int bluefield_edac_mc_probe(struct platform_device *pdev)
 	edac_mc_free(mci);
 
 	return ret;
-
 }
 
 static void bluefield_edac_mc_remove(struct platform_device *pdev)