Re: [PATCH v5 3/3] PCI: qcom: add support for IPQ60xx PCIe controller

[Bjorn Helgaas <helgaas@kernel.org>]

Capitalize subject line to match history, i.e.,

  $ git log --oneline drivers/pci/controller/dwc/pcie-qcom.c
  3f13d611aa6b PCI: qcom: Use __be16 type to store return value from cpu_to_be16()
  4e0e90539bb0 PCI: qcom: Fix an error handling path in 'qcom_pcie_probe()'
  45a3ec891370 PCI: qcom: Add sc8180x compatible
  aa9c0df98c29 PCI: qcom: Switch pcie_1_pipe_clk_src after PHY init in SC7280
  b89ff410253d PCI: qcom: Replace ops with struct pcie_cfg in pcie match data
  2cfef1971aea PCI: qcom: Use PHY_REFCLK_USE_PAD only for ipq8064
  7081556f81f7 PCI: qcom: Add support for ddrss_sf_tbu clock
  4c9398822106 PCI: qcom: Add support for configuring BDF to SID mapping for SM8250
  e1dd639e374a PCI: qcom: Add SM8250 SoC support

A good one would be:

  PCI: qcom: Add IPQ60xx support

We already know this is a PCIe controller, and it's nice to have the
important words like "IPQ60xx" early in the message so they don't get
truncated or wrapped.

On Mon, Jan 24, 2022 at 06:27:31PM +0200, Baruch Siach wrote:
> From: Selvam Sathappan Periakaruppan <speriaka@codeaurora.org>
> 
> IPQ60xx series of SoCs have one port of PCIe gen 3. Add support for that
> platform.
> 
> The code is based on downstream[1] Codeaurora kernel v5.4 (branch
> win.linuxopenwrt.2.0).
> 
> Split out the DBI registers access part from .init into .post_init. DBI
> registers are only accessible after phy_power_on().
> 
> [1] https://source.codeaurora.org/quic/qsdk/oss/kernel/linux-ipq-5.4/
> 
> Signed-off-by: Selvam Sathappan Periakaruppan <speriaka@codeaurora.org>
> Signed-off-by: Baruch Siach <baruch.siach@siklu.com>
> ---
> v5:
> 
>   * Remove comments from qcom_pcie_init_2_9_0() (Bjorn Andersson)
> 
> v4:
> 
>   * Rebase on v5.16-rc1
> 
> v3:
>   * Drop speed setup; rely on generic code (Rob Herring)
> 
>   * Drop unused CLK_RATE macros (Bjorn Helgaas)
> 
>   * Minor formatting fixes (Bjorn Helgaas)
> 
>   * Add reference to downstream Codeaurora kernel tree (Bjorn Helgaas)
> 
> v2:
>   * Drop ATU configuration; rely on common code instead
> 
>   * Use more common register macros
> 
>   * Use bulk clk and reset APIs
> ---
>  drivers/pci/controller/dwc/pcie-designware.h |   1 +
>  drivers/pci/controller/dwc/pcie-qcom.c       | 137 +++++++++++++++++++
>  2 files changed, 138 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index ea87809ee298..279c3778a13b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -76,6 +76,7 @@
>  
>  #define GEN3_RELATED_OFF			0x890
>  #define GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL	BIT(0)
> +#define GEN3_RELATED_OFF_RXEQ_RGRDLESS_RXTS	BIT(13)
>  #define GEN3_RELATED_OFF_GEN3_EQ_DISABLE	BIT(16)
>  #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT	24
>  #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK	GENMASK(25, 24)
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index c19cd506ed3f..5d47e572da44 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -52,6 +52,10 @@
>  #define PCIE20_PARF_DBI_BASE_ADDR		0x168
>  #define PCIE20_PARF_SLV_ADDR_SPACE_SIZE		0x16C
>  #define PCIE20_PARF_MHI_CLOCK_RESET_CTRL	0x174
> +#define AHB_CLK_EN				BIT(0)
> +#define MSTR_AXI_CLK_EN				BIT(1)
> +#define BYPASS					BIT(4)
> +
>  #define PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT	0x178
>  #define PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT_V2	0x1A8
>  #define PCIE20_PARF_LTSSM			0x1B0
> @@ -171,6 +175,11 @@ struct qcom_pcie_resources_2_7_0 {
>  	struct clk *ref_clk_src;
>  };
>  
> +struct qcom_pcie_resources_2_9_0 {
> +	struct clk_bulk_data clks[5];
> +	struct reset_control *rst;
> +};
> +
>  union qcom_pcie_resources {
>  	struct qcom_pcie_resources_1_0_0 v1_0_0;
>  	struct qcom_pcie_resources_2_1_0 v2_1_0;
> @@ -178,6 +187,7 @@ union qcom_pcie_resources {
>  	struct qcom_pcie_resources_2_3_3 v2_3_3;
>  	struct qcom_pcie_resources_2_4_0 v2_4_0;
>  	struct qcom_pcie_resources_2_7_0 v2_7_0;
> +	struct qcom_pcie_resources_2_9_0 v2_9_0;
>  };
>  
>  struct qcom_pcie;
> @@ -1297,6 +1307,119 @@ static void qcom_pcie_post_deinit_2_7_0(struct qcom_pcie *pcie)
>  	clk_disable_unprepare(res->pipe_clk);
>  }
>  
> +static int qcom_pcie_get_resources_2_9_0(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_9_0 *res = &pcie->res.v2_9_0;
> +	struct dw_pcie *pci = pcie->pci;
> +	struct device *dev = pci->dev;
> +	int ret;
> +
> +	res->clks[0].id = "iface";
> +	res->clks[1].id = "axi_m";
> +	res->clks[2].id = "axi_s";
> +	res->clks[3].id = "axi_bridge";
> +	res->clks[4].id = "rchng";
> +
> +	ret = devm_clk_bulk_get(dev, ARRAY_SIZE(res->clks), res->clks);
> +	if (ret < 0)
> +		return ret;
> +
> +	res->rst = devm_reset_control_array_get_exclusive(dev);
> +	if (IS_ERR(res->rst))
> +		return PTR_ERR(res->rst);
> +
> +	return 0;
> +}
> +
> +static void qcom_pcie_deinit_2_9_0(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_9_0 *res = &pcie->res.v2_9_0;
> +
> +	clk_bulk_disable_unprepare(ARRAY_SIZE(res->clks), res->clks);
> +}
> +
> +static int qcom_pcie_init_2_9_0(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_9_0 *res = &pcie->res.v2_9_0;
> +	struct device *dev = pcie->pci->dev;
> +	int ret;
> +
> +	ret = reset_control_assert(res->rst);
> +	if (ret) {
> +		dev_err(dev, "reset assert failed (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	usleep_range(2000, 2500);

Where do these sleep durations come from?  If they're specified
somewhere by PCIe, can you include a citation, e.g., a section number
in the spec.

> +	ret = reset_control_deassert(res->rst);
> +	if (ret) {
> +		dev_err(dev, "reset deassert failed (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	usleep_range(2000, 2500);
> +
> +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
> +	if (ret)
> +		goto err_reset;
> +
> +	return 0;
> +
> +err_reset:
> +	reset_control_assert(res->rst);
> +
> +	return ret;
> +}
> +
> +static int qcom_pcie_post_init_2_9_0(struct qcom_pcie *pcie)
> +{
> +	struct dw_pcie *pci = pcie->pci;
> +	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +	u32 val;
> +	int i;
> +
> +	writel(SLV_ADDR_SPACE_SZ,
> +		pcie->parf + PCIE20_v3_PARF_SLV_ADDR_SPACE_SIZE);
> +
> +	val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
> +	val &= ~BIT(0);
> +	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
> +
> +	writel(0, pcie->parf + PCIE20_PARF_DBI_BASE_ADDR);
> +
> +	writel(DEVICE_TYPE_RC, pcie->parf + PCIE20_PARF_DEVICE_TYPE);
> +	writel(BYPASS | MSTR_AXI_CLK_EN | AHB_CLK_EN,
> +		pcie->parf + PCIE20_PARF_MHI_CLOCK_RESET_CTRL);
> +	writel(GEN3_RELATED_OFF_RXEQ_RGRDLESS_RXTS
> +		| GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL,
> +		pci->dbi_base + GEN3_RELATED_OFF);
> +
> +	writel(MST_WAKEUP_EN | SLV_WAKEUP_EN | MSTR_ACLK_CGC_DIS
> +		| SLV_ACLK_CGC_DIS | CORE_CLK_CGC_DIS |
> +		AUX_PWR_DET | L23_CLK_RMV_DIS | L1_CLK_RMV_DIS,
> +		pcie->parf + PCIE20_PARF_SYS_CTRL);
> +
> +	writel(0, pcie->parf + PCIE20_PARF_Q2A_FLUSH);
> +
> +	dw_pcie_dbi_ro_wr_en(pci);
> +	writel(PCIE_CAP_LINK1_VAL, pci->dbi_base + offset + PCI_EXP_SLTCAP);

Is "PCIE_CAP_LINK1_VAL" misnamed?  If it's being written to
PCI_EXP_SLTCAP, seems like it should be named something about a
*slot*, not a *link*.

Or is this an error and it should this be written to PCI_EXP_LNKCAP
instead?

Could PCIE_CAP_LINK1_VAL be defined in terms of PCI_EXP_SLTCAP_* or
PCI_EXP_LNKCAP_*?

> +	/* Configure PCIe link capabilities for ASPM */
> +	val = readl(pci->dbi_base + offset + PCI_EXP_LNKCAP);
> +	val &= ~PCI_EXP_LNKCAP_ASPMS;
> +	writel(val, pci->dbi_base + offset + PCI_EXP_LNKCAP);

Thanks for using the standard PCI_EXP_LNKCAP and similar #defines.
Does this mean you don't advertise any ASPM support on this platform?
If so, that's fine, but the comment could be more specific.
"Configure" doesn't give any hint about *how* they are configured.

> +	writel(PCI_EXP_DEVCTL2_COMP_TMOUT_DIS, pci->dbi_base + offset +
> +			PCI_EXP_DEVCTL2);
> +
> +	for (i = 0; i < 256; i++)
> +		writel(0x0, pcie->parf + PCIE20_PARF_BDF_TO_SID_TABLE_N
> +				+ (4 * i));
> +
> +	return 0;
> +}
> +
>  static int qcom_pcie_link_up(struct dw_pcie *pci)
>  {
>  	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> @@ -1487,6 +1610,15 @@ static const struct qcom_pcie_ops ops_1_9_0 = {
>  	.config_sid = qcom_pcie_config_sid_sm8250,
>  };
>  
> +/* Qcom IP rev.: 2.9.0  Synopsys IP rev.: 5.00a */
> +static const struct qcom_pcie_ops ops_2_9_0 = {
> +	.get_resources = qcom_pcie_get_resources_2_9_0,
> +	.init = qcom_pcie_init_2_9_0,
> +	.post_init = qcom_pcie_post_init_2_9_0,
> +	.deinit = qcom_pcie_deinit_2_9_0,
> +	.ltssm_enable = qcom_pcie_2_3_2_ltssm_enable,
> +};
> +
>  static const struct qcom_pcie_cfg apq8084_cfg = {
>  	.ops = &ops_1_0_0,
>  };
> @@ -1520,6 +1652,10 @@ static const struct qcom_pcie_cfg sc7280_cfg = {
>  	.pipe_clk_need_muxing = true,
>  };
>  
> +static const struct qcom_pcie_cfg ipq6018_cfg = {
> +	.ops = &ops_2_9_0,
> +};
> +
>  static const struct dw_pcie_ops dw_pcie_ops = {
>  	.link_up = qcom_pcie_link_up,
>  	.start_link = qcom_pcie_start_link,
> @@ -1629,6 +1765,7 @@ static const struct of_device_id qcom_pcie_match[] = {
>  	{ .compatible = "qcom,pcie-sm8250", .data = &sm8250_cfg },
>  	{ .compatible = "qcom,pcie-sc8180x", .data = &sm8250_cfg },
>  	{ .compatible = "qcom,pcie-sc7280", .data = &sc7280_cfg },
> +	{ .compatible = "qcom,pcie-ipq6018", .data = &ipq6018_cfg },
>  	{ }
>  };
>  
> -- 
> 2.34.1
> 
> 
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