Date:   Wed, 13 Dec 2017 17:50:30 +0100
From:   Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        adouglas@...ence.com, stelford@...ence.com, dgary@...ence.com,
        kgopi@...ence.com, eandrews@...ence.com,
        thomas.petazzoni@...e-electrons.com, sureshp@...ence.com,
        nsekhar@...com, linux-kernel@...r.kernel.org, robh@...nel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 5/5] PCI: cadence: add EndPoint Controller driver for
 Cadence PCIe controller

Hi Kishon,

Le 05/12/2017 à 10:19, Kishon Vijay Abraham I a écrit :
> Hi,
> 
> On Friday 01 December 2017 05:50 PM, Lorenzo Pieralisi wrote:
>> On Thu, Nov 23, 2017 at 04:01:50PM +0100, Cyrille Pitchen wrote:
>>> This patch adds support to the Cadence PCIe controller in endpoint mode.
>>
>> Please add a brief description to the log to describe the most salient
>> features.
>>
>>> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
>>> ---
>>>  drivers/pci/cadence/Kconfig           |   9 +
>>>  drivers/pci/cadence/Makefile          |   1 +
>>>  drivers/pci/cadence/pcie-cadence-ep.c | 553 ++++++++++++++++++++++++++++++++++
>>>  3 files changed, 563 insertions(+)
>>>  create mode 100644 drivers/pci/cadence/pcie-cadence-ep.c
>>>
>>> diff --git a/drivers/pci/cadence/Kconfig b/drivers/pci/cadence/Kconfig
>>> index 120306cae2aa..b2e6af71f39e 100644
>>> --- a/drivers/pci/cadence/Kconfig
>>> +++ b/drivers/pci/cadence/Kconfig
>>> @@ -21,4 +21,13 @@ config PCIE_CADENCE_HOST
>>>  	  mode. This PCIe controller may be embedded into many different vendors
>>>  	  SoCs.
>>>  
>>> +config PCIE_CADENCE_EP
>>> +	bool "Cadence PCIe endpoint controller"
>>> +	depends on PCI_ENDPOINT
>>> +	select PCIE_CADENCE
>>> +	help
>>> +	  Say Y here if you want to support the Cadence PCIe  controller in
>>> +	  endpoint mode. This PCIe controller may be embedded into many
>>> +	  different vendors SoCs.
>>> +
>>>  endif # PCI_CADENCE
>>> diff --git a/drivers/pci/cadence/Makefile b/drivers/pci/cadence/Makefile
>>> index d57d192d2595..61e9c8d6839d 100644
>>> --- a/drivers/pci/cadence/Makefile
>>> +++ b/drivers/pci/cadence/Makefile
>>> @@ -1,2 +1,3 @@
>>>  obj-$(CONFIG_PCIE_CADENCE) += pcie-cadence.o
>>>  obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
>>> +obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
>>> diff --git a/drivers/pci/cadence/pcie-cadence-ep.c b/drivers/pci/cadence/pcie-cadence-ep.c
>>> new file mode 100644
>>> index 000000000000..a1d761101a9c
>>> --- /dev/null
>>> +++ b/drivers/pci/cadence/pcie-cadence-ep.c
>>> @@ -0,0 +1,553 @@
>>> +/*
>>> + * Cadence PCIe host controller driver.
>>
>> You should update this comment.
>>
>>> + *
>>> + * Copyright (c) 2017 Cadence
>>> + *
>>> + * Author: Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> + * it under the terms of the GNU General Public License version 2 as
>>> + * published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>> + * GNU General Public License for more details.
>>> + *
>>> + * You should have received a copy of the GNU General Public License along with
>>> + * this program.  If not, see <http://www.gnu.org/licenses/>.
>>> + */
>>> +#include <linux/kernel.h>
>>> +#include <linux/of.h>
>>> +#include <linux/pci-epc.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/sizes.h>
>>> +#include <linux/delay.h>
>>
>> Nit: alphabetical order.
>>
>>> +#include "pcie-cadence.h"
>>> +
>>> +#define CDNS_PCIE_EP_MIN_APERTURE		128	/* 128 bytes */
>>> +#define CDNS_PCIE_EP_IRQ_PCI_ADDR_NONE		0x1
>>> +#define CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY	0x3
>>> +
>>> +/**
>>> + * struct cdns_pcie_ep_data - hardware specific data
>>> + * @max_regions: maximum nmuber of regions supported by hardware
>>
>> s/nmuber/number
>>
>>> + */
>>> +struct cdns_pcie_ep_data {
>>> +	size_t				max_regions;
>>> +};
>>> +
>>> +/**
>>> + * struct cdns_pcie_ep - private data for this PCIe endpoint controller driver
>>> + * @pcie: Cadence PCIe controller
>>> + * @data: pointer to a 'struct cdns_pcie_data'
>>> + */
>>> +struct cdns_pcie_ep {
>>> +	struct cdns_pcie		pcie;
>>> +	const struct cdns_pcie_ep_data	*data;
>>> +	struct pci_epc			*epc;
>>> +	unsigned long			ob_region_map;
>>> +	phys_addr_t			*ob_addr;
>>> +	phys_addr_t			irq_phys_addr;
>>> +	void __iomem			*irq_cpu_addr;
>>> +	u64				irq_pci_addr;
>>> +	u8				irq_pending;
>>> +};
>>> +
>>> +static int cdns_pcie_ep_write_header(struct pci_epc *epc,
>>> +				     struct pci_epf_header *hdr)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u8 fn = 0;
>>> +
>>> +	if (fn == 0) {
>>
>> I think there is some code to retrieve fn missing here.
> 
> hmm.. the endpoint core has to send the function number which right now it's
> not doing though it has the function number info in pci_epf.

Would it be OK if I add a new patch in the next series adding a
'struct pcie_epf *epf' as a 2nd argument to all handlers in the
'struct pcie_epc_ops'? This way I could have access to epf->func_no as needed.

Best regards,

Cyrille

>>
>>> +		u32 id = CDNS_PCIE_LM_ID_VENDOR(hdr->vendorid) |
>>> +			 CDNS_PCIE_LM_ID_SUBSYS(hdr->subsys_vendor_id);
>>> +		cdns_pcie_writel(pcie, CDNS_PCIE_LM_ID, id);
>>> +	}
>>> +	cdns_pcie_ep_fn_writew(pcie, fn, PCI_DEVICE_ID, hdr->deviceid);
>>> +	cdns_pcie_ep_fn_writeb(pcie, fn, PCI_REVISION_ID, hdr->revid);
>>> +	cdns_pcie_ep_fn_writeb(pcie, fn, PCI_CLASS_PROG, hdr->progif_code);
>>> +	cdns_pcie_ep_fn_writew(pcie, fn, PCI_CLASS_DEVICE,
>>> +			       hdr->subclass_code | hdr->baseclass_code << 8);
>>> +	cdns_pcie_ep_fn_writeb(pcie, fn, PCI_CACHE_LINE_SIZE,
>>> +			       hdr->cache_line_size);
>>> +	cdns_pcie_ep_fn_writew(pcie, fn, PCI_SUBSYSTEM_ID, hdr->subsys_id);
>>> +	cdns_pcie_ep_fn_writeb(pcie, fn, PCI_INTERRUPT_PIN, hdr->interrupt_pin);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int cdns_pcie_ep_set_bar(struct pci_epc *epc, enum pci_barno bar,
>>> +				dma_addr_t bar_phys, size_t size, int flags)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 addr0, addr1, reg, cfg, b, aperture, ctrl;
>>> +	u8 fn = 0;
> 
> Here too endpoint core should send the function number..
>>> +	u64 sz;
>>> +
>>> +	/* BAR size is 2^(aperture + 7) */
>>> +	sz = max_t(size_t, size, CDNS_PCIE_EP_MIN_APERTURE);
>>> +	sz = 1ULL << fls64(sz - 1);
>>> +	aperture = ilog2(sz) - 7; /* 128B -> 0, 256B -> 1, 512B -> 2, ... */
>>> +
>>> +	if ((flags & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
>>> +		ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_IO_32BITS;
>>> +	} else {
>>> +		bool is_prefetch = !!(flags & PCI_BASE_ADDRESS_MEM_PREFETCH);
>>> +		bool is_64bits = sz > SZ_2G;
>>> +
>>> +		if (is_64bits && (bar & 1))
>>> +			return -EINVAL;
>>> +
>>> +		switch (is_64bits << 1 | is_prefetch) {
>>
>> I would not mind implementing this as a nested if-else, I am not a big
>> fan of using bool this way.
>>
>>> +		case 0:
>>> +			ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_MEM_32BITS;
>>> +			break;
>>> +
>>> +		case 1:
>>> +			ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_PREFETCH_MEM_32BITS;
>>> +			break;
>>> +
>>> +		case 2:
>>> +			ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_MEM_64BITS;
>>> +			break;
>>> +
>>> +		case 3:
>>> +			ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_PREFETCH_MEM_64BITS;
>>> +			break;
>>> +		}
>>> +	}
>>> +
>>> +	addr0 = lower_32_bits(bar_phys);
>>> +	addr1 = upper_32_bits(bar_phys);
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR0(fn, bar),
>>> +			 addr0);
> 
> It would be nice if you can have defines for CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR0
> included in this patch rather than "PCI: cadence: Add host driver for Cadence
> PCIe controller". All EP specific functions in header file should be included here.
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR1(fn, bar),
>>> +			 addr1);
>>
>> Is fn always 0 ?
>>
>>> +	if (bar < BAR_4) {
>>> +		reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG0(fn);
>>> +		b = bar;
>>> +	} else {
>>> +		reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG1(fn);
>>> +		b = bar - BAR_4;
>>> +	}
>>> +
>>> +	cfg = cdns_pcie_readl(pcie, reg);
>>> +	cfg &= ~(CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE_MASK(b) |
>>> +		 CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL_MASK(b));
>>> +	cfg |= (CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE(b, aperture) |
>>> +		CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL(b, ctrl));
>>> +	cdns_pcie_writel(pcie, reg, cfg);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void cdns_pcie_ep_clear_bar(struct pci_epc *epc, enum pci_barno bar)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 reg, cfg, b, ctrl;
>>> +	u8 fn = 0;
> 
> Here too endpoint core should send the function number..
>>> +
>>> +	if (bar < BAR_4) {
>>> +		reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG0(fn);
>>> +		b = bar;
>>> +	} else {
>>> +		reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG1(fn);
>>> +		b = bar - BAR_4;
>>> +	}
>>> +
>>> +	ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_DISABLED;
>>> +	cfg = cdns_pcie_readl(pcie, reg);
>>> +	cfg &= ~(CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE_MASK(b) |
>>> +		 CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL_MASK(b));
>>> +	cfg |= CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL_MASK(ctrl);
>>> +	cdns_pcie_writel(pcie, reg, cfg);
>>> +
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR0(fn, bar), 0);
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR1(fn, bar), 0);
>>> +}
>>> +
>>> +static int cdns_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
>>> +				 u64 pci_addr, size_t size)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 r;
>>> +
>>> +	r = find_first_zero_bit(&ep->ob_region_map, sizeof(ep->ob_region_map));
>>
>> Second argument must be in bits not bytes.
>>
>> https://marc.info/?l=linux-pci&m=151179781225513&w=2
>>
>>> +	if (r >= ep->data->max_regions - 1) {
>>> +		dev_err(&epc->dev, "no free outbound region\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	cdns_pcie_set_outbound_region(pcie, r, false, addr, pci_addr, size);
>>> +
>>> +	set_bit(r, &ep->ob_region_map);
>>> +	ep->ob_addr[r] = addr;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void cdns_pcie_ep_unmap_addr(struct pci_epc *epc, phys_addr_t addr)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 r;
>>> +
>>> +	for (r = 0; r < ep->data->max_regions - 1; r++)
>>> +		if (ep->ob_addr[r] == addr)
>>> +			break;
>>> +
>>> +	if (r >= ep->data->max_regions - 1)
>>
>> == ?
>>
>>> +		return;
>>> +
>>> +	cdns_pcie_reset_outbound_region(pcie, r);
>>> +
>>> +	ep->ob_addr[r] = 0;
>>> +	clear_bit(r, &ep->ob_region_map);
>>> +}
>>> +
>>> +static int cdns_pcie_ep_set_msi(struct pci_epc *epc, u8 mmc)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
>>> +	u16 flags;
>>> +	u8 fn = 0;
>>> +
>>> +	/* Validate the ID of the MSI Capability structure. */
>>> +	if (cdns_pcie_ep_fn_readb(pcie, fn, cap) != PCI_CAP_ID_MSI)
>>> +		return -EINVAL;
>>> +
>>> +	/*
>>> +	 * Set the Multiple Message Capable bitfield into the Message Control
>>> +	 * register.
>>> +	 */
>>> +	flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
>>> +	flags = (flags & ~PCI_MSI_FLAGS_QMASK) | (mmc << 1);
>>> +	flags |= PCI_MSI_FLAGS_64BIT;
>>> +	flags &= ~PCI_MSI_FLAGS_MASKBIT;
> 
> Any reason why "Per-vector masking capable" is reset?
>>> +	cdns_pcie_ep_fn_writew(pcie, fn, cap + PCI_MSI_FLAGS, flags);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int cdns_pcie_ep_get_msi(struct pci_epc *epc)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
>>> +	u16 flags, mmc, mme;
>>> +	u8 fn = 0;
>>> +
>>> +	/* Validate the ID of the MSI Capability structure. */
>>> +	if (cdns_pcie_ep_fn_readb(pcie, fn, cap) != PCI_CAP_ID_MSI)
>>> +		return -EINVAL;
>>> +
>>> +	/* Validate that the MSI feature is actually enabled. */
>>> +	flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
>>> +	if (!(flags & PCI_MSI_FLAGS_ENABLE))
>>> +		return -EINVAL;
>>> +
>>> +	/*
>>> +	 * Get the Multiple Message Enable bitfield from the Message Control
>>> +	 * register.
>>> +	 */
>>> +	mmc = (flags & PCI_MSI_FLAGS_QMASK) >> 1;
>>> +	mme = (flags & PCI_MSI_FLAGS_QSIZE) >> 4;
>>> +	if (mme > mmc)
>>> +		mme = mmc;
>>> +	if (mme > 5)
>>> +		mme = 5;
> 
> I'm not sure if both these above checks are required..
>>
>> You should comment on what this 5 means and why it is fine to cap mme.
>>
>>> +
>>> +	return mme;
>>> +}
>>> +
>>> +static void cdns_pcie_ep_assert_intx(struct cdns_pcie_ep *ep, u8 fn,
>>> +				     u8 intx, bool is_asserted)
>>> +{
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 r = ep->data->max_regions - 1;
>>> +	u32 offset;
>>> +	u16 status;
>>> +	u8 msg_code;
>>> +
>>> +	intx &= 3;
>>> +
>>> +	/* Set the outbound region if needed. */
>>> +	if (unlikely(ep->irq_pci_addr != CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY)) {
>>> +		/* Last region was reserved for IRQ writes. */
>>> +		cdns_pcie_set_outbound_region_for_normal_msg(pcie, r,
>>> +							     ep->irq_phys_addr);
>>> +		ep->irq_pci_addr = CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY;
>>> +	}
>>> +
>>> +	if (is_asserted) {
>>> +		ep->irq_pending |= BIT(intx);
>>> +		msg_code = MSG_CODE_ASSERT_INTA + intx;
>>> +	} else {
>>> +		ep->irq_pending &= ~BIT(intx);
>>> +		msg_code = MSG_CODE_DEASSERT_INTA + intx;
>>> +	}
>>> +
>>> +	status = cdns_pcie_ep_fn_readw(pcie, fn, PCI_STATUS);
>>> +	if (((status & PCI_STATUS_INTERRUPT) != 0) ^ (ep->irq_pending != 0)) {
>>> +		status ^= PCI_STATUS_INTERRUPT;
>>> +		cdns_pcie_ep_fn_writew(pcie, fn, PCI_STATUS, status);
>>> +	}
> 
> here you are setting the PCI_STATUS_INTERRUPT even before sending the ASSERT
> message.
>>> +
>>> +	offset = CDNS_PCIE_NORMAL_MSG_ROUTING(MSG_ROUTING_LOCAL) |
>>> +		 CDNS_PCIE_NORMAL_MSG_CODE(msg_code) |
>>> +		 CDNS_PCIE_MSG_NO_DATA;
>>> +	writel(0, ep->irq_cpu_addr + offset);
>>> +}
>>> +
>>> +static int cdns_pcie_ep_send_legacy_irq(struct cdns_pcie_ep *ep, u8 fn, u8 intx)
>>> +{
>>> +	u16 cmd;
>>> +
>>> +	cmd = cdns_pcie_ep_fn_readw(&ep->pcie, fn, PCI_COMMAND);
>>> +	if (cmd & PCI_COMMAND_INTX_DISABLE)
>>> +		return -EINVAL;
>>> +
>>> +	cdns_pcie_ep_assert_intx(ep, fn, intx, true);
>>> +	mdelay(1);
>>
>> Add a comment please to explain the mdelay value.
>>
>>> +	cdns_pcie_ep_assert_intx(ep, fn, intx, false);
>>> +	return 0;
>>> +}
>>> +
>>> +static int cdns_pcie_ep_raise_irq(struct pci_epc *epc,
>>> +				  enum pci_epc_irq_type type, u8 interrupt_num)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
>>> +	u16 flags, mmc, mme, data, data_mask;
>>> +	u8 msi_count;
>>> +	u64 pci_addr, pci_addr_mask = 0xff;
>>> +	u8 fn = 0;
>>> +
>>> +	/* Handle legacy IRQ. */
>>> +	if (type == PCI_EPC_IRQ_LEGACY)
>>> +		return cdns_pcie_ep_send_legacy_irq(ep, fn, 0);
>>> +
>>> +	/* Otherwise MSI. */
>>> +	if (type != PCI_EPC_IRQ_MSI)
>>> +		return -EINVAL;
> 
> MSI-X?
>>> +
>>> +	/* Check whether the MSI feature has been enabled by the PCI host. */
>>> +	flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
>>> +	if (!(flags & PCI_MSI_FLAGS_ENABLE))
>>> +		return -EINVAL;
>>> +
>>> +	/* Get the number of enabled MSIs */
>>> +	mmc = (flags & PCI_MSI_FLAGS_QMASK) >> 1;
>>> +	mme = (flags & PCI_MSI_FLAGS_QSIZE) >> 4;
>>> +	if (mme > mmc)
>>> +		mme = mmc;
>>> +	if (mme > 5)
>>> +		mme = 5;
>>
>> Same comment as above.
>>
>>> +	msi_count = 1 << mme;
>>> +	if (!interrupt_num || interrupt_num > msi_count)
>>> +		return -EINVAL;
>>> +
>>> +	/* Compute the data value to be written. */
>>> +	data_mask = msi_count - 1;
>>> +	data = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_DATA_64);
>>> +	data = (data & ~data_mask) | ((interrupt_num - 1) & data_mask);
>>> +
>>> +	/* Get the PCI address where to write the data into. */
>>> +	pci_addr = cdns_pcie_ep_fn_readl(pcie, fn, cap + PCI_MSI_ADDRESS_HI);
>>> +	pci_addr <<= 32;
>>> +	pci_addr |= cdns_pcie_ep_fn_readl(pcie, fn, cap + PCI_MSI_ADDRESS_LO);
>>> +	pci_addr &= GENMASK_ULL(63, 2);
>>> +
>>> +	/* Set the outbound region if needed. */
>>> +	if (unlikely(ep->irq_pci_addr != pci_addr)) {
>>> +		/* Last region was reserved for IRQ writes. */
>>> +		cdns_pcie_set_outbound_region(pcie, ep->data->max_regions - 1,
>>> +					      false,
>>> +					      ep->irq_phys_addr,
>>> +					      pci_addr & ~pci_addr_mask,
>>> +					      pci_addr_mask + 1);
>>> +		ep->irq_pci_addr = pci_addr;
>>> +	}
>>> +	writew(data, ep->irq_cpu_addr + (pci_addr & pci_addr_mask));
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int cdns_pcie_ep_start(struct pci_epc *epc)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	struct pci_epf *epf;
>>> +	u32 cfg;
>>> +	u8 fn = 0;
>>> +
>>> +	/* Enable this endpoint function. */
>>> +	cfg = cdns_pcie_readl(pcie, CDNS_PCIE_LM_EP_FUNC_CFG);
>>> +	cfg |= BIT(fn);
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, cfg);
>>> +
>>> +	/*
>>> +	 * Already linked-up: don't call directly pci_epc_linkup() because we've
>>> +	 * already locked the epc->lock.
>>> +	 */
> 
> Not sure what you mean by linked-up here?
>>> +	list_for_each_entry(epf, &epc->pci_epf, list)
>>> +		pci_epf_linkup(epf);
> 
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void cdns_pcie_ep_stop(struct pci_epc *epc)
>>> +{
>>> +	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>>> +	struct cdns_pcie *pcie = &ep->pcie;
>>> +	u32 cfg;
>>> +	u8 fn = 0;
>>> +
>>> +	/* Disable this endpoint function (function 0 can't be disabled). */
>>
>> I do not understand this comment and how it applies to the code,
>> in other words fn is always 0 here (so it can't be disabled)
>> I do not understand what this code is there for.
>>
>>> +	cfg = cdns_pcie_readl(pcie, CDNS_PCIE_LM_EP_FUNC_CFG);
>>> +	cfg &= ~BIT(fn);
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, cfg);
>>> +}
>>> +
>>> +static const struct pci_epc_ops cdns_pcie_epc_ops = {
>>> +	.write_header	= cdns_pcie_ep_write_header,
>>> +	.set_bar	= cdns_pcie_ep_set_bar,
>>> +	.clear_bar	= cdns_pcie_ep_clear_bar,
>>> +	.map_addr	= cdns_pcie_ep_map_addr,
>>> +	.unmap_addr	= cdns_pcie_ep_unmap_addr,
>>> +	.set_msi	= cdns_pcie_ep_set_msi,
>>> +	.get_msi	= cdns_pcie_ep_get_msi,
>>> +	.raise_irq	= cdns_pcie_ep_raise_irq,
>>> +	.start		= cdns_pcie_ep_start,
>>> +	.stop		= cdns_pcie_ep_stop,
>>> +};
>>> +
>>> +static const struct cdns_pcie_ep_data cdns_pcie_ep_data = {
>>> +	.max_regions	= 16,
>>> +};
>>
>> As I mentioned in patch 3, should this be set-up with DT ?
>>
>> Thanks,
>> Lorenzo
>>
>>> +
>>> +static const struct of_device_id cdns_pcie_ep_of_match[] = {
>>> +	{ .compatible = "cdns,cdns-pcie-ep",
>>> +	  .data = &cdns_pcie_ep_data },
>>> +
>>> +	{ },
>>> +};
>>> +
>>> +static int cdns_pcie_ep_probe(struct platform_device *pdev)
>>> +{
>>> +	struct device *dev = &pdev->dev;
>>> +	struct device_node *np = dev->of_node;
>>> +	const struct of_device_id *of_id;
>>> +	struct cdns_pcie_ep *ep;
>>> +	struct cdns_pcie *pcie;
>>> +	struct pci_epc *epc;
>>> +	struct resource *res;
>>> +	size_t max_regions;
>>> +	int ret;
>>> +
>>> +	ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
>>> +	if (!ep)
>>> +		return -ENOMEM;
>>> +
>>> +	platform_set_drvdata(pdev, ep);
>>> +
>>> +	pcie = &ep->pcie;
>>> +	pcie->is_rc = false;
>>> +
>>> +	of_id = of_match_node(cdns_pcie_ep_of_match, np);
>>> +	ep->data = (const struct cdns_pcie_ep_data *)of_id->data;
>>> +
>>> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg");
>>> +	pcie->reg_base = devm_ioremap_resource(dev, res);
>>> +	if (IS_ERR(pcie->reg_base)) {
>>> +		dev_err(dev, "missing \"reg\"\n");
>>> +		return PTR_ERR(pcie->reg_base);
>>> +	}
>>> +
>>> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem");
>>> +	if (!res) {
>>> +		dev_err(dev, "missing \"mem\"\n");
>>> +		return -EINVAL;
>>> +	}
>>> +	pcie->mem_res = res;
>>> +
>>> +	max_regions = ep->data->max_regions;
>>> +	ep->ob_addr = devm_kzalloc(dev, max_regions * sizeof(*ep->ob_addr),
>>> +				   GFP_KERNEL);
>>> +	if (!ep->ob_addr)
>>> +		return -ENOMEM;
>>> +
>>> +	pm_runtime_enable(dev);
>>> +	ret = pm_runtime_get_sync(dev);
>>> +	if (ret < 0) {
>>> +		dev_err(dev, "pm_runtime_get_sync() failed\n");
>>> +		goto err_get_sync;
>>> +	}
>>> +
>>> +	/* Disable all but function 0 (anyway BIT(0) is hardwired to 1). */
>>> +	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, BIT(0));
> 
> why disable all functions?
>>> +
>>> +	epc = devm_pci_epc_create(dev, &cdns_pcie_epc_ops);
>>> +	if (IS_ERR(epc)) {
>>> +		dev_err(dev, "failed to create epc device\n");
>>> +		ret = PTR_ERR(epc);
>>> +		goto err_init;
>>> +	}
>>> +
>>> +	ep->epc = epc;
>>> +	epc_set_drvdata(epc, ep);
>>> +
>>> +	ret = of_property_read_u8(np, "max-functions", &epc->max_functions);
>>> +	if (ret < 0)
>>> +		epc->max_functions = 1;
>>> +
>>> +	ret = pci_epc_mem_init(epc, pcie->mem_res->start,
>>> +			       resource_size(pcie->mem_res));
>>> +	if (ret < 0) {
>>> +		dev_err(dev, "failed to initialize the memory space\n");
>>> +		goto err_init;
>>> +	}
>>> +
>>> +	ep->irq_cpu_addr = pci_epc_mem_alloc_addr(epc, &ep->irq_phys_addr,
>>> +						  SZ_128K);
> 
> Any reason why you chose SZ_128K?
> 
> Thanks
> Kishon
> 


-- 
Cyrille Pitchen, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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