Date:   Mon, 4 Dec 2017 15:56:42 +0100
From:   Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     bhelgaas@...gle.com, kishon@...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 Lorenzo,

Le 01/12/2017 à 13:20, Lorenzo Pieralisi a écrit :
> 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.
>

I've used some "u8 fn = 0;" when implementing every handler of
'struct pci_epc_ops' because the current API of the EPC library supports
only one function for now but I guess this will change soon.

So I've implement each handler as if a new 'fn' parameter were added to the
handler prototype. I guess it would make sense to add such a parameter to
the pci_epc_*() functions in pci-epc-core.c.
 
>> +		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;
>> +	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.
>

It did it this way to cope with the 80 columns rule but I will try to do it
with nested if-elst statements. The macro names I've chosen are quite long!

>> +		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);
>> +	cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR1(fn, bar),
>> +			 addr1);
> 
> Is fn always 0 ?
>

If the API of the EPC library is updated, fn could be something else but 0
later but for now, fn is actually 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;
>> +
>> +	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
>

OK, thanks!

>> +	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)
> 
> == ?
>

I will change that.

>> +		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;
>> +	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;
> 
> 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);
>> +	}
>> +
>> +	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.
>

Honestly, I don't know for this value: I've just adapted the source code
from what was already done by dra7xx_pcie_raise_legacy_irq() from
drivers/pci/dwc/pci-dra7xx.c.

>> +	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;
>> +
>> +	/* 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.
>> +	 */
>> +	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.
>

fn == 0 for the same reason as for other 'struct pci_epc_ops' handlers.
I added this comment above because BIT(0) is hard-wired to 1: in other word
function 0 is the only one that can't be disabled.

So the current code actually does nothing. I've implemented anyway still
hoping that the API would change so function other than 0 could be used.

>> +	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 ?
>

OK, I'll move it as a DT property.

Best regards,

Cyrille

> 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));
>> +
>> +	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);
>> +	if (!ep->irq_cpu_addr) {
>> +		dev_err(dev, "failed to reserve memory space for MSI\n");
>> +		ret = -ENOMEM;
>> +		goto free_epc_mem;
>> +	}
>> +	ep->irq_pci_addr = CDNS_PCIE_EP_IRQ_PCI_ADDR_NONE;
>> +
>> +	return 0;
>> +
>> + free_epc_mem:
>> +	pci_epc_mem_exit(epc);
>> +
>> + err_init:
>> +	pm_runtime_put_sync(dev);
>> +
>> + err_get_sync:
>> +	pm_runtime_disable(dev);
>> +
>> +	return ret;
>> +}
>> +
>> +static struct platform_driver cdns_pcie_ep_driver = {
>> +	.driver = {
>> +		.name = "cdns-pcie-ep",
>> +		.of_match_table = cdns_pcie_ep_of_match,
>> +	},
>> +	.probe = cdns_pcie_ep_probe,
>> +};
>> +builtin_platform_driver(cdns_pcie_ep_driver);
>> -- 
>> 2.11.0
>>
> 


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

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