Re: [PATCH v5 5/5] PCI: dwc: Add common send PME_Turn_Off message method

Manivannan Sadhasivam
2024-04-05T06:24:39Z

On Tue, Mar 19, 2024 at 12:07:15PM -0400, Frank Li wrote:

PCI: dwc: Add generic MSG TLP support for sending PME_Turn_Off during system suspend

> Reserve space at end of first IORESOURCE_MEM window as message TLP MMIO
> window. This space's size is 'region_align'.
>
> Set outbound ATU map memory write to send PCI message. So one MMIO write
> can trigger a PCI message, such as PME_Turn_Off.
>
> Add common dwc_pme_turn_off() function.
>
> Call dwc_pme_turn_off() to send out PME_Turn_Off message in general
> dw_pcie_suspend_noirq() if there are not platform callback pme_turn_off()
> exist.
>

How about:

"Instead of relying on the vendor specific implementations to send the
PME_Turn_Off message, let's introduce a generic way of sending the message using
the MSG TLP.

This is achieved by reserving a region for MSG TLP of size 'pci->region_align',
at the end of the first IORESOURCE_MEM window of the host bridge. And then
sending the PME_Turn_Off message during system suspend with the help of iATU.

It should be noted that this generic implementation is optional for the glue
drivers and can be overridden by a custom 'pme_turn_off' callback."

> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
> drivers/pci/controller/dwc/pcie-designware.h | 3 +
> 2 files changed, 93 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 267687ab33cbc..d5723fce7a894 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -393,6 +393,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
> return 0;
> }
>
> +static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct resource_entry *win;
> + struct resource *res;
> +
> + win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> + if (win) {
> + res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
> + if (!res)
> + return;
> +
> + /* Reserve last region_align block as message TLP space */
> + res->start = win->res->end - pci->region_align + 1;
> + res->end = win->res->end;

Don't you need to adjust the host bridge window size and end address?

> + res->name = "msg";
> + res->flags = win->res->flags | IORESOURCE_BUSY;
> +

Shouldn't this resource be added back to the host bridge?

> + if (!request_resource(win->res, res))

Why can't you use devm_ helper to manage the resource, since the lifetime of the
resource is till dw_pcie_host_deinit()?

> + pp->msg_res = res;
> + else
> + devm_kfree(pci->dev, res);
> + }
> +}
> +
> int dw_pcie_host_init(struct dw_pcie_rp *pp)
> {
> struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -479,6 +504,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
>
> dw_pcie_iatu_detect(pci);
>
> + /* Need call after dw_pcie_iatu_detect() before dw_pcie_setup_rc() */

It'd be better to add the reason also i.,e

/*
* Allocate the resource for MSG TLP before programming the iATU
* outbound window in dw_pcie_setup_rc(). Since the allocation depends
* on the value of 'region_align', this has to be done after
* dw_pcie_iatu_detect().
*/

> + if (pp->use_atu_msg)

Who is setting this flag?

> + dw_pcie_host_request_msg_tlp_res(pp);
> +
> ret = dw_pcie_edma_detect(pci);
> if (ret)
> goto err_free_msi;
> @@ -536,6 +565,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
>
> dw_pcie_edma_remove(pci);
>
> + if (pp->msg_res) {
> + release_resource(pp->msg_res);
> + devm_kfree(pci->dev, pp->msg_res);
> + }
> +
> if (pp->has_msi_ctrl)
> dw_pcie_free_msi(pp);
>
> @@ -697,6 +731,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> atu.pci_addr = entry->res->start - entry->offset;
> atu.size = resource_size(entry->res);
>
> + /* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */
> + if (pp->msg_res && pp->msg_res->parent == entry->res)
> + atu.size -= resource_size(pp->msg_res);

If you adjust the bridge window above, then this won't be needed.

> +
> ret = dw_pcie_prog_outbound_atu(pci, &atu);
> if (ret) {
> dev_err(pci->dev, "Failed to set MEM range %pr\n",
> @@ -728,6 +766,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
> pci->num_ob_windows);
>
> + pp->msg_atu_index = i;
> +
> i = 0;
> resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
> if (resource_type(entry->res) != IORESOURCE_MEM)
> @@ -833,11 +873,54 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> }
> EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
>
> +/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */
> +static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
> +{
> + struct dw_pcie_ob_atu_cfg atu = { 0 };
> + void __iomem *m;

*mem

> + int ret;
> +
> + if (pci->num_ob_windows <= pci->pp.msg_atu_index)
> + return -EINVAL;
> +
> + if (!pci->pp.msg_res)
> + return -EINVAL;
> +
> + atu.code = PCIE_MSG_CODE_PME_TURN_OFF;
> + atu.routing = PCIE_MSG_TYPE_R_BC;
> + atu.type = PCIE_ATU_TYPE_MSG;
> + atu.size = resource_size(pci->pp.msg_res);
> + atu.index = pci->pp.msg_atu_index;
> +
> + if (!atu.size) {
> + dev_dbg(pci->dev,
> + "atu memory map windows is zero, please check 'msg' reg in dts\n");

You are already checking the existence of the 'pci->pp.msg_res' region above. So
shouldn't that be sufficient enough? Can the size be 0, if the region exist?

- Mani

> + return -ENOMEM;
> + }
> +
> + atu.cpu_addr = pci->pp.msg_res->start;
> +
> + ret = dw_pcie_prog_outbound_atu(pci, &atu);
> + if (ret)
> + return ret;
> +
> + m = ioremap(atu.cpu_addr, pci->region_align);
> + if (!m)
> + return -ENOMEM;
> +
> + /* A dummy write is converted to a Msg TLP */
> + writel(0, m);
> +
> + iounmap(m);
> +
> + return 0;
> +}
> +
> int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> {
> u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> u32 val;
> - int ret;
> + int ret = 0;
>
> /*
> * If L1SS is supported, then do not put the link into L2 as some
> @@ -849,10 +932,13 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
> return 0;
>
> - if (!pci->pp.ops->pme_turn_off)
> - return 0;
> + if (pci->pp.ops->pme_turn_off)
> + pci->pp.ops->pme_turn_off(&pci->pp);
> + else
> + ret = dw_pcie_pme_turn_off(pci);
>
> - pci->pp.ops->pme_turn_off(&pci->pp);
> + if (ret)
> + return ret;
>
> ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
> PCIE_PME_TO_L2_TIMEOUT_US/10,
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 703b50bc5e0f1..dca5de4c6e877 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -341,6 +341,9 @@ struct dw_pcie_rp {
> struct pci_host_bridge *bridge;
> raw_spinlock_t lock;
> DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
> + bool use_atu_msg;
> + int msg_atu_index;
> + struct resource *msg_res;
> };
>
> struct dw_pcie_ep_ops {
>
> --
> 2.34.1
>

--
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