RE: [PATCHv9 10/12] PCI: mobiveil: Add PCIe Gen4 RC driver for NXP Layerscape SoCs

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Hi Andrew,

Thanks a lot for your comments!

> -----Original Message-----
> From: Andrew Murray <andrew.murray@xxxxxxx>
> Sent: 2020年1月13日 20:03
> To: Z.q. Hou <zhiqiang.hou@xxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; robh+dt@xxxxxxxxxx; arnd@xxxxxxxx;
> mark.rutland@xxxxxxx; l.subrahmanya@xxxxxxxxxxxxxx;
> shawnguo@xxxxxxxxxx; m.karthikeyan@xxxxxxxxxxxxxx; Leo Li
> <leoyang.li@xxxxxxx>; lorenzo.pieralisi@xxxxxxx;
> catalin.marinas@xxxxxxx; will.deacon@xxxxxxx; Mingkai Hu
> <mingkai.hu@xxxxxxx>; M.h. Lian <minghuan.lian@xxxxxxx>; Xiaowei Bao
> <xiaowei.bao@xxxxxxx>
> Subject: Re: [PATCHv9 10/12] PCI: mobiveil: Add PCIe Gen4 RC driver for NXP
> Layerscape SoCs
> 
> On Wed, Nov 20, 2019 at 03:46:23AM +0000, Z.q. Hou wrote:
> > From: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>
> >
> > This PCIe controller is based on the Mobiveil GPEX IP, which is
> > compatible with the PCI Express™ Base Specification, Revision 4.0.
> >
> > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>
> > Reviewed-by: Minghuan Lian <Minghuan.Lian@xxxxxxx>
> > ---
> >  drivers/pci/controller/mobiveil/Kconfig       |  10 +
> >  drivers/pci/controller/mobiveil/Makefile      |   1 +
> >  .../mobiveil/pcie-layerscape-gen4.c           | 274
> ++++++++++++++++++
> >  .../pci/controller/mobiveil/pcie-mobiveil.h   |  16 +-
> >  4 files changed, 299 insertions(+), 2 deletions(-)  create mode
> > 100644 drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
> >
> > diff --git a/drivers/pci/controller/mobiveil/Kconfig
> > b/drivers/pci/controller/mobiveil/Kconfig
> > index 64343c07bfed..c823be8dab1c 100644
> > --- a/drivers/pci/controller/mobiveil/Kconfig
> > +++ b/drivers/pci/controller/mobiveil/Kconfig
> > @@ -21,4 +21,14 @@ config PCIE_MOBIVEIL_PLAT
> >  	  Soft IP. It has up to 8 outbound and inbound windows
> >  	  for address translation and it is a PCIe Gen4 IP.
> >
> > +config PCIE_LAYERSCAPE_GEN4
> > +	bool "Freescale Layerscape PCIe Gen4 controller"
> > +	depends on PCI
> > +	depends on OF && (ARM64 || ARCH_LAYERSCAPE)
> > +	depends on PCI_MSI_IRQ_DOMAIN
> > +	select PCIE_MOBIVEIL_HOST
> > +	help
> > +	  Say Y here if you want PCIe Gen4 controller support on
> > +	  Layerscape SoCs. The PCIe controller can work in RC or
> > +	  EP mode according to RCW[HOST_AGT_PEX] setting.
> 
> I think you can remove the last sentence - it doesn't give any value to users of
> KConfig.

OK, will remove it in v10.

> 
> 
> >  endmenu
> > diff --git a/drivers/pci/controller/mobiveil/Makefile
> > b/drivers/pci/controller/mobiveil/Makefile
> > index 9fb6d1c6504d..99d879de32d6 100644
> > --- a/drivers/pci/controller/mobiveil/Makefile
> > +++ b/drivers/pci/controller/mobiveil/Makefile
> > @@ -2,3 +2,4 @@
> >  obj-$(CONFIG_PCIE_MOBIVEIL) += pcie-mobiveil.o
> >  obj-$(CONFIG_PCIE_MOBIVEIL_HOST) += pcie-mobiveil-host.o
> >  obj-$(CONFIG_PCIE_MOBIVEIL_PLAT) += pcie-mobiveil-plat.o
> > +obj-$(CONFIG_PCIE_LAYERSCAPE_GEN4) += pcie-layerscape-gen4.o
> > diff --git a/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
> > b/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
> > new file mode 100644
> > index 000000000000..6c0d3e2532db
> > --- /dev/null
> > +++ b/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
> > @@ -0,0 +1,274 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * PCIe Gen4 host controller driver for NXP Layerscape SoCs
> > + *
> > + * Copyright 2019 NXP
> > + *
> > + * Author: Zhiqiang Hou <Zhiqiang.Hou@xxxxxxx>  */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/init.h>
> > +#include <linux/of_pci.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/of_address.h>
> > +#include <linux/pci.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/resource.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/regmap.h>
> > +
> > +#include "pcie-mobiveil.h"
> > +
> > +/* LUT and PF control registers */
> > +#define PCIE_LUT_OFF			0x80000
> > +#define PCIE_PF_OFF			0xc0000
> > +#define PCIE_PF_INT_STAT		0x18
> > +#define PF_INT_STAT_PABRST		BIT(31)
> > +
> > +#define PCIE_PF_DBG			0x7fc
> > +#define PF_DBG_LTSSM_MASK		0x3f
> > +#define PF_DBG_LTSSM_L0			0x2d /* L0 state */
> > +#define PF_DBG_WE			BIT(31)
> > +#define PF_DBG_PABR			BIT(27)
> > +
> > +#define to_ls_pcie_g4(x)		platform_get_drvdata((x)->pdev)
> > +
> > +struct ls_pcie_g4 {
> > +	struct mobiveil_pcie pci;
> > +	struct delayed_work dwork;
> > +	int irq;
> > +};
> > +
> > +static inline u32 ls_pcie_g4_lut_readl(struct ls_pcie_g4 *pcie, u32
> > +off) {
> > +	return ioread32(pcie->pci.csr_axi_slave_base + PCIE_LUT_OFF + off);
> > +}
> > +
> > +static inline void ls_pcie_g4_lut_writel(struct ls_pcie_g4 *pcie,
> > +					 u32 off, u32 val)
> > +{
> > +	iowrite32(val, pcie->pci.csr_axi_slave_base + PCIE_LUT_OFF + off); }
> > +
> > +static inline u32 ls_pcie_g4_pf_readl(struct ls_pcie_g4 *pcie, u32
> > +off) {
> > +	return ioread32(pcie->pci.csr_axi_slave_base + PCIE_PF_OFF + off); }
> > +
> > +static inline void ls_pcie_g4_pf_writel(struct ls_pcie_g4 *pcie,
> > +					u32 off, u32 val)
> > +{
> > +	iowrite32(val, pcie->pci.csr_axi_slave_base + PCIE_PF_OFF + off); }
> > +
> > +static bool ls_pcie_g4_is_bridge(struct ls_pcie_g4 *pcie) {
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +	u32 header_type;
> > +
> > +	header_type = mobiveil_csr_readb(mv_pci, PCI_HEADER_TYPE);
> > +	header_type &= 0x7f;
> > +
> > +	return header_type == PCI_HEADER_TYPE_BRIDGE; }
> > +
> > +static int ls_pcie_g4_link_up(struct mobiveil_pcie *pci) {
> > +	struct ls_pcie_g4 *pcie = to_ls_pcie_g4(pci);
> > +	u32 state;
> > +
> > +	state = ls_pcie_g4_pf_readl(pcie, PCIE_PF_DBG);
> > +	state =	state & PF_DBG_LTSSM_MASK;
> > +
> > +	if (state == PF_DBG_LTSSM_L0)
> > +		return 1;
> > +
> > +	return 0;
> > +}
> > +
> > +static void ls_pcie_g4_disable_interrupt(struct ls_pcie_g4 *pcie) {
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +
> > +	mobiveil_csr_writel(mv_pci, 0, PAB_INTP_AMBA_MISC_ENB); }
> > +
> > +static void ls_pcie_g4_enable_interrupt(struct ls_pcie_g4 *pcie) {
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +	u32 val;
> > +
> > +	/* Clear the interrupt status */
> > +	mobiveil_csr_writel(mv_pci, 0xffffffff, PAB_INTP_AMBA_MISC_STAT);
> > +
> > +	val = PAB_INTP_INTX_MASK | PAB_INTP_MSI | PAB_INTP_RESET |
> > +	      PAB_INTP_PCIE_UE | PAB_INTP_IE_PMREDI | PAB_INTP_IE_EC;
> > +	mobiveil_csr_writel(mv_pci, val, PAB_INTP_AMBA_MISC_ENB); }
> > +
> > +static void ls_pcie_g4_reinit_hw(struct ls_pcie_g4 *pcie) {
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +	struct device *dev = &mv_pci->pdev->dev;
> > +	u32 val, act_stat;
> > +	int to = 100;
> > +
> > +	/* Poll for pab_csb_reset to set and PAB activity to clear */
> > +	do {
> > +		usleep_range(10, 15);
> > +		val = ls_pcie_g4_pf_readl(pcie, PCIE_PF_INT_STAT);
> > +		act_stat = mobiveil_csr_readl(mv_pci, PAB_ACTIVITY_STAT);
> > +	} while (((val & PF_INT_STAT_PABRST) == 0 || act_stat) && to--);
> > +	if (to < 0) {
> > +		dev_err(dev, "Poll PABRST&PABACT timeout\n");
> > +		return;
> 
> If a timeout happens here - the caller has no idea this has happened and yet
> the following work doesn't get done. Isn't this a problem?

Will change the return value type to 'int' in v10, so that the caller can know the fail.

> 
> > +	}
> > +
> > +	/* clear PEX_RESET bit in PEX_PF0_DBG register */
> > +	val = ls_pcie_g4_pf_readl(pcie, PCIE_PF_DBG);
> > +	val |= PF_DBG_WE;
> > +	ls_pcie_g4_pf_writel(pcie, PCIE_PF_DBG, val);
> > +
> > +	val = ls_pcie_g4_pf_readl(pcie, PCIE_PF_DBG);
> > +	val |= PF_DBG_PABR;
> > +	ls_pcie_g4_pf_writel(pcie, PCIE_PF_DBG, val);
> > +
> > +	val = ls_pcie_g4_pf_readl(pcie, PCIE_PF_DBG);
> > +	val &= ~PF_DBG_WE;
> > +	ls_pcie_g4_pf_writel(pcie, PCIE_PF_DBG, val);
> > +
> > +	mobiveil_host_init(mv_pci, true);
> 
> Can mobiveil_host_init fail?

It should not fail, only register programming operations were left in this function.

> 
> > +
> > +	to = 100;
> > +	while (!ls_pcie_g4_link_up(mv_pci) && to--)
> > +		usleep_range(200, 250);
> > +	if (to < 0)
> > +		dev_err(dev, "PCIe link training timeout\n"); }
> > +
> > +static irqreturn_t ls_pcie_g4_isr(int irq, void *dev_id) {
> > +	struct ls_pcie_g4 *pcie = (struct ls_pcie_g4 *)dev_id;
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +	u32 val;
> > +
> > +	val = mobiveil_csr_readl(mv_pci, PAB_INTP_AMBA_MISC_STAT);
> > +	if (!val)
> > +		return IRQ_NONE;
> > +
> > +	if (val & PAB_INTP_RESET) {
> 
> Can you explain why this is needed (perhaps also in the cover letter)?

The hot reset will result in the RC crash, so need the ISR to reset the RC.

> 
> > +		ls_pcie_g4_disable_interrupt(pcie);
> > +		schedule_delayed_work(&pcie->dwork, msecs_to_jiffies(1));
> > +	}
> > +
> > +	mobiveil_csr_writel(mv_pci, val, PAB_INTP_AMBA_MISC_STAT);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int ls_pcie_g4_interrupt_init(struct mobiveil_pcie *mv_pci) {
> > +	struct ls_pcie_g4 *pcie = to_ls_pcie_g4(mv_pci);
> > +	struct platform_device *pdev = mv_pci->pdev;
> > +	struct device *dev = &pdev->dev;
> > +	int ret;
> > +
> > +	pcie->irq = platform_get_irq_byname(pdev, "intr");
> > +	if (pcie->irq < 0) {
> > +		dev_err(dev, "Can't get 'intr' IRQ, errno = %d\n", pcie->irq);
> > +		return pcie->irq;
> > +	}
> > +	ret = devm_request_irq(dev, pcie->irq, ls_pcie_g4_isr,
> > +			       IRQF_SHARED, pdev->name, pcie);
> > +	if (ret) {
> > +		dev_err(dev, "Can't register PCIe IRQ, errno = %d\n", ret);
> > +		return  ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void ls_pcie_g4_reset(struct work_struct *work) {
> > +	struct delayed_work *dwork = container_of(work, struct delayed_work,
> > +						  work);
> > +	struct ls_pcie_g4 *pcie = container_of(dwork, struct ls_pcie_g4, dwork);
> > +	struct mobiveil_pcie *mv_pci = &pcie->pci;
> > +	u16 ctrl;
> > +
> > +	ctrl = mobiveil_csr_readw(mv_pci, PCI_BRIDGE_CONTROL);
> > +	ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
> > +	mobiveil_csr_writew(mv_pci, ctrl, PCI_BRIDGE_CONTROL);
> > +	ls_pcie_g4_reinit_hw(pcie);
> > +	ls_pcie_g4_enable_interrupt(pcie);
> > +}
> > +
> > +static struct mobiveil_rp_ops ls_pcie_g4_rp_ops = {
> > +	.interrupt_init = ls_pcie_g4_interrupt_init, };
> > +
> > +static const struct mobiveil_pab_ops ls_pcie_g4_pab_ops = {
> > +	.link_up = ls_pcie_g4_link_up,
> > +};
> > +
> > +static int __init ls_pcie_g4_probe(struct platform_device *pdev) {
> > +	struct device *dev = &pdev->dev;
> > +	struct pci_host_bridge *bridge;
> > +	struct mobiveil_pcie *mv_pci;
> > +	struct ls_pcie_g4 *pcie;
> > +	struct device_node *np = dev->of_node;
> > +	int ret;
> > +
> > +	if (!of_parse_phandle(np, "msi-parent", 0)) {
> > +		dev_err(dev, "Failed to find msi-parent\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
> > +	if (!bridge)
> > +		return -ENOMEM;
> > +
> > +	pcie = pci_host_bridge_priv(bridge);
> > +	mv_pci = &pcie->pci;
> > +
> > +	mv_pci->pdev = pdev;
> > +	mv_pci->ops = &ls_pcie_g4_pab_ops;
> > +	mv_pci->rp.ops = &ls_pcie_g4_rp_ops;
> > +	mv_pci->rp.bridge = bridge;
> > +
> > +	platform_set_drvdata(pdev, pcie);
> > +
> > +	INIT_DELAYED_WORK(&pcie->dwork, ls_pcie_g4_reset);
> > +
> > +	ret = mobiveil_pcie_host_probe(mv_pci);
> > +	if (ret) {
> > +		dev_err(dev, "Fail to probe\n");
> > +		return  ret;
> > +	}
> > +
> > +	if (!ls_pcie_g4_is_bridge(pcie))
> 
> Is this a check that could apply to all host bridge drivers and thus live in
> mobiveil_pcie_host_probe?

Yes, will do in v10.

> 
> > +		return -ENODEV;
> > +
> > +	ls_pcie_g4_enable_interrupt(pcie);
> 
> Is there an issue here in that we enable interrupts *after* telling the kernel
> about our controller? (Same applies for bailing if the IP isn't a bridge).

Andrew, I don't understand the issue, can you help to explain?

Thanks,
Zhiqiang

> 
> Thanks,
> 
> Andrew Murray
> 
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id ls_pcie_g4_of_match[] = {
> > +	{ .compatible = "fsl,lx2160a-pcie", },
> > +	{ },
> > +};
> > +
> > +static struct platform_driver ls_pcie_g4_driver = {
> > +	.driver = {
> > +		.name = "layerscape-pcie-gen4",
> > +		.of_match_table = ls_pcie_g4_of_match,
> > +		.suppress_bind_attrs = true,
> > +	},
> > +};
> > +
> > +builtin_platform_driver_probe(ls_pcie_g4_driver, ls_pcie_g4_probe);
> > diff --git a/drivers/pci/controller/mobiveil/pcie-mobiveil.h
> > b/drivers/pci/controller/mobiveil/pcie-mobiveil.h
> > index 750a7fd95bc1..c57a68d2bac4 100644
> > --- a/drivers/pci/controller/mobiveil/pcie-mobiveil.h
> > +++ b/drivers/pci/controller/mobiveil/pcie-mobiveil.h
> > @@ -43,6 +43,8 @@
> >  #define  PAGE_LO_MASK			0x3ff
> >  #define  PAGE_SEL_OFFSET_SHIFT		10
> >
> > +#define PAB_ACTIVITY_STAT		0x81c
> > +
> >  #define PAB_AXI_PIO_CTRL		0x0840
> >  #define  APIO_EN_MASK			0xf
> >
> > @@ -51,8 +53,18 @@
> >
> >  #define PAB_INTP_AMBA_MISC_ENB		0x0b0c
> >  #define PAB_INTP_AMBA_MISC_STAT		0x0b1c
> > -#define  PAB_INTP_INTX_MASK		0x01e0
> > -#define  PAB_INTP_MSI_MASK		0x8
> > +#define  PAB_INTP_RESET			BIT(1)
> > +#define  PAB_INTP_MSI			BIT(3)
> > +#define  PAB_INTP_INTA			BIT(5)
> > +#define  PAB_INTP_INTB			BIT(6)
> > +#define  PAB_INTP_INTC			BIT(7)
> > +#define  PAB_INTP_INTD			BIT(8)
> > +#define  PAB_INTP_PCIE_UE		BIT(9)
> > +#define  PAB_INTP_IE_PMREDI		BIT(29)
> > +#define  PAB_INTP_IE_EC			BIT(30)
> > +#define  PAB_INTP_MSI_MASK		PAB_INTP_MSI
> > +#define  PAB_INTP_INTX_MASK		(PAB_INTP_INTA |
> PAB_INTP_INTB |\
> > +					PAB_INTP_INTC | PAB_INTP_INTD)
> >
> >  #define PAB_AXI_AMAP_CTRL(win)		PAB_REG_ADDR(0x0ba0,
> win)
> >  #define  WIN_ENABLE_SHIFT		0
> > --
> > 2.17.1
> >




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