[PATCH v3 5/5] PCI: qcom: Add support for configuring BDF to SID mapping for SM8250

[Manivannan Sadhasivam]

For SM8250, we need to write the BDF to SID mapping in PCIe controller
register space for proper working. This is accomplished by extracting
the BDF and SID values from "iommu-map" property in DT and writing those
in the register address calculated from the hash value of BDF. In case
of collisions, the index of the next entry will also be written.

For the sake of it, let's introduce a "config_sid" callback and do it
conditionally for SM8250.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
 drivers/pci/controller/dwc/Kconfig     |   1 +
 drivers/pci/controller/dwc/pcie-qcom.c | 138 +++++++++++++++++++++++++
 2 files changed, 139 insertions(+)

diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index 044a3761c44f..3e9ccdc45ee1 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -169,6 +169,7 @@ config PCIE_QCOM
 	depends on OF && (ARCH_QCOM || COMPILE_TEST)
 	depends on PCI_MSI_IRQ_DOMAIN
 	select PCIE_DW_HOST
+	select CRC8
 	help
 	  Say Y here to enable PCIe controller support on Qualcomm SoCs. The
 	  PCIe controller uses the DesignWare core plus Qualcomm-specific
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 3167ad66413d..5e1b88ffc23c 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/crc8.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
@@ -57,6 +58,7 @@
 #define PCIE20_PARF_SID_OFFSET			0x234
 #define PCIE20_PARF_BDF_TRANSLATE_CFG		0x24C
 #define PCIE20_PARF_DEVICE_TYPE			0x1000
+#define PCIE20_PARF_BDF_TO_SID_TABLE_N		0x2000
 
 #define PCIE20_ELBI_SYS_CTRL			0x04
 #define PCIE20_ELBI_SYS_CTRL_LT_ENABLE		BIT(0)
@@ -101,6 +103,9 @@
 
 #define QCOM_PCIE_2_1_0_MAX_SUPPLY	3
 #define QCOM_PCIE_2_1_0_MAX_CLOCKS	5
+
+#define QCOM_PCIE_CRC8_POLYNOMIAL (BIT(2) | BIT(1) | BIT(0))
+
 struct qcom_pcie_resources_2_1_0 {
 	struct clk_bulk_data clks[QCOM_PCIE_2_1_0_MAX_CLOCKS];
 	struct reset_control *pci_reset;
@@ -183,6 +188,16 @@ struct qcom_pcie_ops {
 	void (*deinit)(struct qcom_pcie *pcie);
 	void (*post_deinit)(struct qcom_pcie *pcie);
 	void (*ltssm_enable)(struct qcom_pcie *pcie);
+	int (*config_sid)(struct qcom_pcie *pcie);
+};
+
+/* sid info structure */
+struct qcom_pcie_sid_info_t {
+	u16 bdf;
+	u8 pcie_sid;
+	u8 hash;
+	u32 smmu_sid;
+	u32 value;
 };
 
 struct qcom_pcie {
@@ -193,6 +208,8 @@ struct qcom_pcie {
 	struct phy *phy;
 	struct gpio_desc *reset;
 	const struct qcom_pcie_ops *ops;
+	struct qcom_pcie_sid_info_t *sid_info;
+	u32 sid_info_len;
 	int gen;
 };
 
@@ -1257,6 +1274,120 @@ static int qcom_pcie_link_up(struct dw_pcie *pci)
 	return !!(val & PCI_EXP_LNKSTA_DLLLA);
 }
 
+static int qcom_pcie_get_iommu_map(struct qcom_pcie *pcie)
+{
+	/* iommu map structure */
+	struct {
+		u32 bdf;
+		u32 phandle;
+		u32 smmu_sid;
+		u32 smmu_sid_len;
+	} *map;
+	struct device *dev = pcie->pci->dev;
+	int i, size = 0;
+	u32 smmu_sid_base;
+
+	of_get_property(dev->of_node, "iommu-map", &size);
+	if (!size)
+		return 0;
+
+	map = kzalloc(size, GFP_KERNEL);
+	if (!map)
+		return -ENOMEM;
+
+	of_property_read_u32_array(dev->of_node,
+		"iommu-map", (u32 *)map, size / sizeof(u32));
+
+	pcie->sid_info_len = size / (sizeof(*map));
+	pcie->sid_info = devm_kcalloc(dev, pcie->sid_info_len,
+				sizeof(*pcie->sid_info), GFP_KERNEL);
+	if (!pcie->sid_info) {
+		kfree(map);
+		return -ENOMEM;
+	}
+
+	/* Extract the SMMU SID base from the first entry of iommu-map */
+	smmu_sid_base = map[0].smmu_sid;
+	for (i = 0; i < pcie->sid_info_len; i++) {
+		pcie->sid_info[i].bdf = map[i].bdf;
+		pcie->sid_info[i].smmu_sid = map[i].smmu_sid;
+		pcie->sid_info[i].pcie_sid =
+				pcie->sid_info[i].smmu_sid - smmu_sid_base;
+	}
+
+	kfree(map);
+
+	return 0;
+}
+
+static int qcom_pcie_config_sid_sm8250(struct qcom_pcie *pcie)
+{
+	void __iomem *bdf_to_sid_base = pcie->parf +
+		PCIE20_PARF_BDF_TO_SID_TABLE_N;
+	u8 qcom_pcie_crc8_table[CRC8_TABLE_SIZE];
+	int ret, i;
+
+	ret = qcom_pcie_get_iommu_map(pcie);
+	if (ret)
+		return ret;
+
+	if (!pcie->sid_info)
+		return 0;
+
+	crc8_populate_msb(qcom_pcie_crc8_table, QCOM_PCIE_CRC8_POLYNOMIAL);
+
+	/* Registers need to be zero out first */
+	memset_io(bdf_to_sid_base, 0, CRC8_TABLE_SIZE * sizeof(u32));
+
+	/* Initial setup for boot */
+	for (i = 0; i < pcie->sid_info_len; i++) {
+		struct qcom_pcie_sid_info_t *sid_info = &pcie->sid_info[i];
+		u16 bdf_be = cpu_to_be16(sid_info->bdf);
+		u32 val;
+		u8 hash;
+
+		hash = crc8(qcom_pcie_crc8_table, (u8 *)&bdf_be, sizeof(bdf_be),
+			0);
+
+		val = readl(bdf_to_sid_base + hash * sizeof(u32));
+
+		/* If there is a collision, look for next available entry */
+		while (val) {
+			u8 current_hash = hash++;
+			u8 next_mask = 0xff;
+
+			/* If NEXT field is NULL then update it with next hash */
+			if (!(val & next_mask)) {
+				int j;
+
+				val |= (u32)hash;
+				writel(val, bdf_to_sid_base +
+					current_hash * sizeof(u32));
+
+				/* Look for sid_info of current hash and update it */
+				for (j = 0; j < pcie->sid_info_len; j++) {
+					if (pcie->sid_info[j].hash !=
+						current_hash)
+						continue;
+
+					pcie->sid_info[j].value = val;
+					break;
+				}
+			}
+
+			val = readl(bdf_to_sid_base + hash * sizeof(u32));
+		}
+
+		val = sid_info->bdf << 16 | sid_info->pcie_sid << 8 | 0;
+		writel(val, bdf_to_sid_base + hash * sizeof(u32));
+
+		sid_info->hash = hash;
+		sid_info->value = val;
+	}
+
+	return 0;
+}
+
 static int qcom_pcie_host_init(struct pcie_port *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -1290,6 +1421,12 @@ static int qcom_pcie_host_init(struct pcie_port *pp)
 	if (ret)
 		goto err;
 
+	if (pcie->ops->config_sid) {
+		ret = pcie->ops->config_sid(pcie);
+		if (ret)
+			goto err;
+	}
+
 	return 0;
 err:
 	qcom_ep_reset_assert(pcie);
@@ -1367,6 +1504,7 @@ static const struct qcom_pcie_ops ops_1_9_0 = {
 	.ltssm_enable = qcom_pcie_2_3_2_ltssm_enable,
 	.post_init = qcom_pcie_post_init_2_7_0,
 	.post_deinit = qcom_pcie_post_deinit_2_7_0,
+	.config_sid = qcom_pcie_config_sid_sm8250,
 };
 
 static const struct dw_pcie_ops dw_pcie_ops = {
-- 
2.17.1