Commit e1a4ec1a authored by Frank Li's avatar Frank Li Committed by Bjorn Helgaas
Browse files

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

Instead of relying on the vendor specific implementations to send the
PME_Turn_Off message, 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.

The reason for reserving the MSG TLP region at the end of the
IORESOURCE_MEM is to avoid generating holes in between, because when the
region is allocated using allocate_resource(), memory will be allocated
from the start of the window. Later, if memory gets allocated for an
endpoint of size bigger than 'region_align', there will be a hole between
MSG TLP region and endpoint memory.

This generic implementation is optional for the glue drivers and can be
overridden by a custom 'pme_turn_off' callback.

Link: https://lore.kernel.org/linux-pci/20240418-pme_msg-v8-5-a54265c39742@nxp.com


Signed-off-by: default avatarFrank Li <Frank.Li@nxp.com>
Signed-off-by: default avatarKrzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
parent 9972b177

drivers/pci/controller/dwc/pcie-designware-host.c

+90 −5
Original line number Diff line number Diff line
@@ -398,6 +398,32 @@ 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;



		/*

		 * Allocate MSG TLP region of size 'region_align' at the end of

		 * the host bridge window.

		 */

		res->start = win->res->end - pci->region_align + 1;

		res->end = win->res->end;

		res->name = "msg";

		res->flags = win->res->flags | IORESOURCE_BUSY;



		if (!devm_request_resource(pci->dev, win->res, res))

			pp->msg_res = res;

	}

}



int dw_pcie_host_init(struct dw_pcie_rp *pp)

{

	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -484,6 +510,18 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) 


	dw_pcie_iatu_detect(pci);



	/*

	 * 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().

	 *

	 * Glue drivers need to set 'use_atu_msg' before dw_pcie_host_init() to

	 * make use of the generic MSG TLP implementation.

	 */

	if (pp->use_atu_msg)

		dw_pcie_host_request_msg_tlp_res(pp);



	ret = dw_pcie_edma_detect(pci);

	if (ret)

		goto err_free_msi;
@@ -700,6 +738,12 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp) 
		atu.type = PCIE_ATU_TYPE_MEM;

		atu.cpu_addr = entry->res->start;

		atu.pci_addr = entry->res->start - entry->offset;



		/* Adjust iATU size if MSG TLP region was allocated before */

		if (pp->msg_res && pp->msg_res->parent == entry->res)

			atu.size = resource_size(entry->res) -

					resource_size(pp->msg_res);

		else

			atu.size = resource_size(entry->res);



		ret = dw_pcie_prog_outbound_atu(pci, &atu);
@@ -733,6 +777,8 @@ 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)
@@ -838,11 +884,47 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp) 
}

EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);



static int dw_pcie_pme_turn_off(struct dw_pcie *pci)

{

	struct dw_pcie_ob_atu_cfg atu = { 0 };

	void __iomem *mem;

	int ret;



	if (pci->num_ob_windows <= pci->pp.msg_atu_index)

		return -ENOSPC;



	if (!pci->pp.msg_res)

		return -ENOSPC;



	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;



	atu.cpu_addr = pci->pp.msg_res->start;



	ret = dw_pcie_prog_outbound_atu(pci, &atu);

	if (ret)

		return ret;



	mem = ioremap(atu.cpu_addr, pci->region_align);

	if (!mem)

		return -ENOMEM;



	/* A dummy write is converted to a Msg TLP */

	writel(0, mem);



	iounmap(mem);



	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
@@ -854,10 +936,13 @@ 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);



	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,

drivers/pci/controller/dwc/pcie-designware.h

+3 −0
Original line number Diff line number Diff line
@@ -340,6 +340,9 @@ 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 {