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SubjectRe: [PATCH v2 5/5] PCI: qcom: Add support for configuring BDF to SID mapping for SM8250
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Hi Mani,

On 9/30/20 6:09 PM, Manivannan Sadhasivam wrote:
> 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.

This describes what the patch is doing. But why? Is that done in the
other DWC low-level drivers or this is qcom specialty?

>
> 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@linaro.org>
> ---
> 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 44db91861b47..a7f05b78315b 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 {

why _t postfix? Maybe qcom_pcie_sid ?

SID - Stream ID ?

> + 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));

iommu-map is a standard DT property why we have to parse it manually?

> +
> + 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 */

Could you elaborate more what the code below is trying to achieve. Is
that connected to bootloaders?

> + 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_sm8250 = {
> .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 = {
>

--
regards,
Stan

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