Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

Lorenzo Pieralisi
2023-08-16T15:30:54Z

On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
>
> Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> suspend state.
>
> Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
> 1 file changed, 121 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> index ed5fb492fe084..b49f654335fd7 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> @@ -8,9 +8,11 @@
> * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
> */
>
> +#include <linux/delay.h>
> #include <linux/kernel.h>
> #include <linux/interrupt.h>
> #include <linux/init.h>
> +#include <linux/iopoll.h>
> #include <linux/of_pci.h>
> #include <linux/of_platform.h>
> #include <linux/of_address.h>
> @@ -20,6 +22,7 @@
> #include <linux/mfd/syscon.h>
> #include <linux/regmap.h>
>
> +#include "../../pci.h"
> #include "pcie-designware.h"
>
> /* PEX Internal Configuration Registers */
> @@ -27,12 +30,26 @@
> #define PCIE_ABSERR 0x8d0 /* Bridge Slave Error Response Register */
> #define PCIE_ABSERR_SETTING 0x9401 /* Forward error of non-posted request */
>
> +/* PF Message Command Register */
> +#define LS_PCIE_PF_MCR 0x2c
> +#define PF_MCR_PTOMR BIT(0)
> +#define PF_MCR_EXL2S BIT(1)
> +
> #define PCIE_IATU_NUM 6
>
> +struct ls_pcie_drvdata {
> + const u32 pf_off;
> + bool pm_support;
> +};
> +
> struct ls_pcie {
> struct dw_pcie *pci;
> + const struct ls_pcie_drvdata *drvdata;
> + void __iomem *pf_base;
> + bool big_endian;
> };
>
> +#define ls_pcie_pf_readl_addr(addr) ls_pcie_pf_readl(pcie, addr)
> #define to_ls_pcie(x) dev_get_drvdata((x)->dev)
>
> static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> }
>
> +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> +{
> + if (pcie->big_endian)
> + return ioread32be(pcie->pf_base + off);
> +
> + return ioread32(pcie->pf_base + off);
> +}
> +
> +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> +{
> + if (pcie->big_endian)
> + iowrite32be(val, pcie->pf_base + off);
> + else
> + iowrite32(val, pcie->pf_base + off);
> +}
> +
> +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct ls_pcie *pcie = to_ls_pcie(pci);
> + u32 val;
> + int ret;
> +
> + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> + val |= PF_MCR_PTOMR;
> + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> +
> + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> + val, !(val & PF_MCR_PTOMR),
> + PCIE_PME_TO_L2_TIMEOUT_US/10,
> + PCIE_PME_TO_L2_TIMEOUT_US);
> + if (ret)
> + dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> +}
> +
> +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct ls_pcie *pcie = to_ls_pcie(pci);
> + u32 val;
> + int ret;
> +
> + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> + val |= PF_MCR_EXL2S;
> + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);

What is this write transaction generating in HW ?

Why is it needed ? Shouldn't L2 exit happen automatically
in HW ?

> +
> + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> + val, !(val & PF_MCR_EXL2S),
> + PCIE_PME_TO_L2_TIMEOUT_US/10,
> + PCIE_PME_TO_L2_TIMEOUT_US);

And why is the timeout value the same used for the PME_turn_off message ?

Thanks,
Lorenzo

> + if (ret)
> + dev_err(pcie->pci->dev, "L2 exit timeout\n");
> +}
> +
> static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> {
> struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -91,18 +162,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
>
> static const struct dw_pcie_host_ops ls_pcie_host_ops = {
> .host_init = ls_pcie_host_init,
> + .pme_turn_off = ls_pcie_send_turnoff_msg,
> + .exit_from_l2 = ls_pcie_exit_from_l2,
> +};
> +
> +static const struct ls_pcie_drvdata ls1021a_drvdata = {
> +};
> +
> +static const struct ls_pcie_drvdata layerscape_drvdata = {
> + .pf_off = 0xc0000,
> + .pm_support = true,
> };
>
> static const struct of_device_id ls_pcie_of_match[] = {
> - { .compatible = "fsl,ls1012a-pcie", },
> - { .compatible = "fsl,ls1021a-pcie", },
> - { .compatible = "fsl,ls1028a-pcie", },
> - { .compatible = "fsl,ls1043a-pcie", },
> - { .compatible = "fsl,ls1046a-pcie", },
> - { .compatible = "fsl,ls2080a-pcie", },
> - { .compatible = "fsl,ls2085a-pcie", },
> - { .compatible = "fsl,ls2088a-pcie", },
> - { .compatible = "fsl,ls1088a-pcie", },
> + { .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
> + { .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
> + { .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
> + { .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
> { },
> };
>
> @@ -121,6 +202,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
> if (!pci)
> return -ENOMEM;
>
> + pcie->drvdata = of_device_get_match_data(dev);
> +
> pci->dev = dev;
> pci->pp.ops = &ls_pcie_host_ops;
>
> @@ -131,6 +214,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
> if (IS_ERR(pci->dbi_base))
> return PTR_ERR(pci->dbi_base);
>
> + pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
> +
> + pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
> +
> if (!ls_pcie_is_bridge(pcie))
> return -ENODEV;
>
> @@ -139,12 +226,37 @@ static int ls_pcie_probe(struct platform_device *pdev)
> return dw_pcie_host_init(&pci->pp);
> }
>
> +static int ls_pcie_suspend_noirq(struct device *dev)
> +{
> + struct ls_pcie *pcie = dev_get_drvdata(dev);
> +
> + if (!pcie->drvdata->pm_support)
> + return 0;
> +
> + return dw_pcie_suspend_noirq(pcie->pci);
> +}
> +
> +static int ls_pcie_resume_noirq(struct device *dev)
> +{
> + struct ls_pcie *pcie = dev_get_drvdata(dev);
> +
> + if (!pcie->drvdata->pm_support)
> + return 0;
> +
> + return dw_pcie_resume_noirq(pcie->pci);
> +}
> +
> +static const struct dev_pm_ops ls_pcie_pm_ops = {
> + NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
> +};
> +
> static struct platform_driver ls_pcie_driver = {
> .probe = ls_pcie_probe,
> .driver = {
> .name = "layerscape-pcie",
> .of_match_table = ls_pcie_of_match,
> .suppress_bind_attrs = true,
> + .pm = &ls_pcie_pm_ops,
> },
> };
> builtin_platform_driver(ls_pcie_driver);
> --
> 2.34.1
>