Re: [PATCH v10 4/6] PCI: hisi: Add PCIe host support for HiSilicon SoC Hip05

From: Bjorn Helgaas <helgaas@kernel.org>
To: Zhou Wang <wangzhou1@hisilicon.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	jingoohan1@gmail.com, pratyush.anand@gmail.com,
	Arnd Bergmann <arnd@arndb.de>,
	linux@arm.linux.org.uk, thomas.petazzoni@free-electrons.com,
	gabriele.paoloni@huawei.com, lorenzo.pieralisi@arm.com,
	james.morse@arm.com, Liviu.Dudau@arm.com, jason@lakedaemon.net,
	robh@kernel.org, gabriel.fernandez@linaro.org,
	Minghuan.Lian@freescale.com, linux-pci@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, zhangjukuo@huawei.com,
	qiuzhenfa@hisilicon.com, liudongdong3@huawei.com,
	qiujiang@huawei.com, xuwei5@hisilicon.com,
	liguozhu@hisilicon.com, Kefeng Wang <wangkefeng.wang@huawei.com>,
	Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH v10 4/6] PCI: hisi: Add PCIe host support for HiSilicon SoC Hip05
Date: Mon, 12 Oct 2015 16:35:45 -0500	[thread overview]
Message-ID: <20151012213545.GA17479@localhost> (raw)
In-Reply-To: <1444445957-239522-5-git-send-email-wangzhou1@hisilicon.com>

[+cc Arnd, Rob]

Hi Zhou,

I have a few minor comments and two questions: one about the fact
all the config accesses are 32 bits, and another about the use of the
"msi-parent" node.

On Sat, Oct 10, 2015 at 10:59:15AM +0800, Zhou Wang wrote:
> This patch adds PCIe host support for HiSilicon SoC Hip05.
> 
> Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
> Signed-off-by: liudongdong <liudongdong3@huawei.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Signed-off-by: qiuzhenfa <qiuzhenfa@hisilicon.com>

This is a pretty long Signed-off-by chain.  If each of these people
created part of this patch, that's fine.  I'm just checking whether
that's the case, or whether some of these should be Reviewed-by,
Suggested-by, etc., per Documentation/SubmittingPatches.

> ---
>  drivers/pci/host/Kconfig     |   8 ++
>  drivers/pci/host/Makefile    |   1 +
>  drivers/pci/host/pcie-hisi.c | 320 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 329 insertions(+)
>  create mode 100644 drivers/pci/host/pcie-hisi.c
> 
> diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> index d5e58ba..ae873be 100644
> --- a/drivers/pci/host/Kconfig
> +++ b/drivers/pci/host/Kconfig
> @@ -145,4 +145,12 @@ config PCIE_IPROC_BCMA
>  	  Say Y here if you want to use the Broadcom iProc PCIe controller
>  	  through the BCMA bus interface
>  
> +config PCI_HISI
> +	depends on OF && ARM64
> +	bool "HiSilicon SoC HIP05 PCIe controller"
> +	select PCIEPORTBUS
> +	select PCIE_DW
> +	help
> +	  Say Y here if you want PCIe controller support on HiSilicon HIP05 SoC
> +
>  endmenu
> diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> index 140d66f..ea1dbf2 100644
> --- a/drivers/pci/host/Makefile
> +++ b/drivers/pci/host/Makefile
> @@ -17,3 +17,4 @@ obj-$(CONFIG_PCI_VERSATILE) += pci-versatile.o
>  obj-$(CONFIG_PCIE_IPROC) += pcie-iproc.o
>  obj-$(CONFIG_PCIE_IPROC_PLATFORM) += pcie-iproc-platform.o
>  obj-$(CONFIG_PCIE_IPROC_BCMA) += pcie-iproc-bcma.o
> +obj-$(CONFIG_PCI_HISI) += pcie-hisi.o
> diff --git a/drivers/pci/host/pcie-hisi.c b/drivers/pci/host/pcie-hisi.c
> new file mode 100644
> index 0000000..26aa0d9
> --- /dev/null
> +++ b/drivers/pci/host/pcie-hisi.c
> @@ -0,0 +1,320 @@
> +/*
> + * PCIe host controller driver for HiSilicon Hip05 SoC
> + *
> + * Copyright (C) 2015 HiSilicon Co., Ltd. http://www.hisilicon.com
> + *
> + * Author: Zhou Wang <wangzhou1@hisilicon.com>
> + *         Dacai Zhu <zhudacai@hisilicon.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.
> + */
> +#include <linux/interrupt.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include "pcie-designware.h"
> +
> +#define PCIE_SUBCTRL_MODE_REG                           0x2800
> +#define PCIE_SUBCTRL_SYS_STATE4_REG                     0x6818
> +#define PCIE_SLV_DBI_MODE                               0x0
> +#define PCIE_SLV_SYSCTRL_MODE                           0x1
> +#define PCIE_SLV_CONTENT_MODE                           0x2
> +#define PCIE_SLV_MSI_ASID                               0x10
> +#define PCIE_LTSSM_LINKUP_STATE                         0x11
> +#define PCIE_LTSSM_STATE_MASK                           0x3F
> +#define PCIE_MSI_ASID_ENABLE                            (0x1 << 12)
> +#define PCIE_MSI_ASID_VALUE                             (0x1 << 16)
> +#define PCIE_MSI_TRANS_ENABLE                           (0x1 << 12)
> +#define PCIE_MSI_TRANS_REG                              0x1c8
> +#define PCIE_MSI_LOW_ADDRESS                            0x1b4
> +#define PCIE_MSI_HIGH_ADDRESS                           0x1c4
> +#define PCIE_GITS_TRANSLATER                            0x10040

"TRANSLATOR" is the more common spelling.  But if you're matching
hardware documentation, you should follow that.

> +#define PCIE_SYS_CTRL20_REG                             0x20
> +#define PCIE_RD_TAB_SEL                                 BIT(31)
> +#define PCIE_RD_TAB_EN                                  BIT(30)
> +
> +#define to_hisi_pcie(x)	container_of(x, struct hisi_pcie, pp)
> +
> +struct hisi_pcie {
> +	struct regmap *subctrl;
> +	void __iomem *reg_base;
> +	u32 port_id;
> +	struct pcie_port pp;
> +};
> +
> +static inline void hisi_pcie_apb_writel(struct hisi_pcie *pcie,
> +					u32 val, u32 reg)
> +{
> +	writel(val, pcie->reg_base + reg);
> +}
> +
> +static inline u32 hisi_pcie_apb_readl(struct hisi_pcie *pcie, u32 reg)
> +{
> +	return readl(pcie->reg_base + reg);
> +}
> +
> +/*
> + * Change mode to indicate the same reg_base to base of PCIe host configure
> + * registers, base of RC configure space or base of vmid/asid context table

It's fine to use lower-case in the C code, but in English text, it
reads a little better to capitalize acronyms like VMID, ASID, APB, AR,
AW, etc.  

> + */
> +static void hisi_pcie_change_apb_mode(struct hisi_pcie *pcie, u32 mode)
> +{
> +	u32 val;
> +	u32 bit_mask;
> +	u32 bit_shift;
> +	u32 port_id = pcie->port_id;
> +	u32 reg = PCIE_SUBCTRL_MODE_REG + 0x100 * port_id;
> +
> +	if ((port_id == 1) || (port_id == 2)) {
> +		bit_mask = 0xc;
> +		bit_shift = 0x2;
> +	} else {
> +		bit_mask = 0x6;
> +		bit_shift = 0x1;
> +	}
> +
> +	regmap_update_bits(pcie->subctrl, reg, bit_mask, mode << bit_shift);
> +}
> +
> +/* Configure vmid/asid table in PCIe host */
> +static void hisi_pcie_config_context(struct hisi_pcie *pcie)
> +{
> +	int i;
> +	u32 val;
> +
> +	/* enable to clean vmid and asid tables though apb bus */
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
> +
> +	val = hisi_pcie_apb_readl(pcie, PCIE_SYS_CTRL20_REG);
> +	/* enable ar channel */
> +	val |= PCIE_RD_TAB_SEL | PCIE_RD_TAB_EN;
> +	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_CONTENT_MODE);
> +
> +	/*
> +	 * init vmid and asid tables for all PCIe devices as 0

s/as 0/to 0./

> +	 * vmid table: 0 ~ 0x3ff, asid table: 0x400 ~ 0x7ff
> +	 */
> +	for (i = 0; i < 0x800; i++)
> +		hisi_pcie_apb_writel(pcie, 0x0, i * 4);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
> +
> +	/* enable aw channel */
> +	val &= (~PCIE_RD_TAB_SEL);
> +	val |= PCIE_RD_TAB_EN;
> +	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_CONTENT_MODE);
> +
> +	for (i = 0; i < 0x800; i++)
> +		hisi_pcie_apb_writel(pcie, 0x0, i * 4);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
> +
> +	val = hisi_pcie_apb_readl(pcie, PCIE_SYS_CTRL20_REG);
> +	/* disable ar channel */
> +	val |= PCIE_RD_TAB_SEL;
> +	val &= (~PCIE_RD_TAB_EN);
> +	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
> +	/* disable aw channel */
> +	val &= ((~PCIE_RD_TAB_SEL) & (~PCIE_RD_TAB_EN));
> +	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_DBI_MODE);
> +}
> +
> +static int hisi_pcie_link_up(struct pcie_port *pp)
> +{
> +	u32 val;
> +	struct hisi_pcie *hisi_pcie = to_hisi_pcie(pp);
> +
> +	regmap_read(hisi_pcie->subctrl, PCIE_SUBCTRL_SYS_STATE4_REG +
> +		    0x100 * hisi_pcie->port_id, &val);
> +
> +	return ((val & PCIE_LTSSM_STATE_MASK) == PCIE_LTSSM_LINKUP_STATE);
> +}
> +
> +static
> +int hisi_pcie_msi_host_init(struct pcie_port *pp, struct msi_controller *chip)

"static int hisi_..." as in other cases (wrap before "struct
msi_controller" instead of before "int hisi_pcie_msi_host_init").

> +{
> +	u64 addr;
> +	struct device_node *msi_node;
> +	struct resource res;
> +	struct device_node *np = pp->dev->of_node;
> +	struct hisi_pcie *pcie = to_hisi_pcie(pp);
> +
> +	msi_node = of_parse_phandle(np, "msi-parent", 0);
> +	if (!msi_node) {
> +		dev_err(pp->dev, "failed to find msi-parent\n");
> +		return -EINVAL;
> +	}
> +	of_address_to_resource(msi_node, 0, &res);

Does this use the "msi-parent" node in the same way as other drivers
do?  I'm sure there must be other places where we extract struct
resource information from an "msi-parent" node, but I don't see them.

I'm trying to verify that this isn't some kind of incompatible
extension of the "msi-parent" property.  I cc'd Arnd and Rob (DT
experts).

> +	addr = res.start + PCIE_GITS_TRANSLATER;
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
> +
> +	hisi_pcie_apb_writel(pcie, addr & 0xffffffff, PCIE_MSI_LOW_ADDRESS);
> +	hisi_pcie_apb_writel(pcie, addr >> 32, PCIE_MSI_HIGH_ADDRESS);
> +	hisi_pcie_apb_writel(pcie, PCIE_MSI_ASID_ENABLE | PCIE_MSI_ASID_VALUE,
> +			     PCIE_SLV_MSI_ASID);
> +	hisi_pcie_apb_writel(pcie, PCIE_MSI_TRANS_ENABLE, PCIE_MSI_TRANS_REG);
> +
> +	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_DBI_MODE);
> +
> +	return 0;
> +}
> +
> +static int hisi_pcie_cfg_write(struct pcie_port *pp, int where, int  size,
> +				u32 val)
> +{
> +	u32 reg_val;
> +	u32 reg;
> +	struct hisi_pcie *pcie = to_hisi_pcie(pp);
> +	void *walker = &reg_val;
> +
> +	walker += (where & 0x3);
> +	reg = where & ~0x3;
> +	if (size == 4)
> +		hisi_pcie_apb_writel(pcie, val, reg);
> +	else if (size == 2) {
> +		reg_val = hisi_pcie_apb_readl(pcie, reg);
> +		*(u16 __force *) walker = val;
> +		hisi_pcie_apb_writel(pcie, reg_val, reg);
> +	} else if (size == 1) {
> +		reg_val = hisi_pcie_apb_readl(pcie, reg);
> +		*(u8 __force *) walker = val;
> +		hisi_pcie_apb_writel(pcie, reg_val, reg);

This has the read/modify/write problem pointed out by Russell King:
http://lkml.kernel.org/r/E1Zenfg-0004d5-Dg@rmk-PC.arm.linux.org.uk

Is the HiSilicon hardware limited to 32-bit config accesses?  If so,
that seems like a hardware implementation defect, and this needs at
least a comment in the code.  When we figure out a good mechanism,
we'll want to taint or warn about this hardware limitation somehow.

> +	} else
> +		return PCIBIOS_BAD_REGISTER_NUMBER;
> +
> +	return PCIBIOS_SUCCESSFUL;
> +}
> +
> +static int hisi_pcie_cfg_read(struct pcie_port *pp, int where, int size,
> +			      u32 *val)
> +{
> +	u32 reg;
> +	u32 reg_val;
> +	struct hisi_pcie *pcie = to_hisi_pcie(pp);
> +	void *walker = &reg_val;
> +
> +	walker += (where & 0x3);
> +	reg = where & ~0x3;
> +	reg_val = hisi_pcie_apb_readl(pcie, reg);
> +
> +	if (size == 1)
> +		*val = *(u8 __force *) walker;
> +	else if (size == 2)
> +		*val = *(u16 __force *) walker;
> +	else if (size != 4)
> +		return PCIBIOS_BAD_REGISTER_NUMBER;
> +
> +	return PCIBIOS_SUCCESSFUL;
> +}
> +
> +static struct pcie_host_ops hisi_pcie_host_ops = {
> +	.link_up = hisi_pcie_link_up,
> +	.msi_host_init = hisi_pcie_msi_host_init,
> +	.wr_own_conf = hisi_pcie_cfg_write,
> +	.rd_own_conf = hisi_pcie_cfg_read,

Under the rule of "do it the same way unless there's a reason to be
different," please put the hisi_pcie_cfg_read() definition before the
hisi_pcie_cfg_write() definition, and change the order of these
function pointers similarly.  That matches the order in the struct
pcie_host_ops definition and in other drivers.

> +};
> +
> +static int __init hisi_add_pcie_port(struct pcie_port *pp,
> +				     struct platform_device *pdev)
> +{
> +	int ret;
> +	u32 port_id;
> +	struct hisi_pcie *hisi_pcie = to_hisi_pcie(pp);
> +
> +	if (of_property_read_u32(pdev->dev.of_node, "port-id", &port_id)) {
> +		dev_err(&pdev->dev, "failed to read port-id\n");
> +		return -EINVAL;
> +	}
> +	if (port_id > 3) {
> +		dev_err(&pdev->dev, "Invalid port-id: %d\n", port_id);
> +		return -EINVAL;
> +	}
> +	hisi_pcie->port_id = port_id;
> +
> +	pp->ops = &hisi_pcie_host_ops;
> +
> +	hisi_pcie_config_context(hisi_pcie);
> +
> +	ret = dw_pcie_host_init(pp);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to initialize host\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int __init hisi_pcie_probe(struct platform_device *pdev)
> +{
> +	struct hisi_pcie *hisi_pcie;
> +	struct pcie_port *pp;
> +	struct resource *reg;
> +	int ret;
> +
> +	hisi_pcie = devm_kzalloc(&pdev->dev, sizeof(*hisi_pcie), GFP_KERNEL);
> +	if (!hisi_pcie)
> +		return -ENOMEM;
> +
> +	pp = &hisi_pcie->pp;
> +	pp->dev = &pdev->dev;
> +
> +	hisi_pcie->subctrl =
> +	syscon_regmap_lookup_by_compatible("hisilicon,pcie-sas-subctrl");

Indent a tab here.

> +	if (IS_ERR(hisi_pcie->subctrl)) {
> +		dev_err(pp->dev, "cannot get subctrl base\n");
> +		return PTR_ERR(hisi_pcie->subctrl);
> +	}
> +
> +	reg = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rc_dbi");
> +	hisi_pcie->reg_base = devm_ioremap_resource(&pdev->dev, reg);
> +	if (IS_ERR(hisi_pcie->reg_base)) {
> +		dev_err(pp->dev, "cannot get rc_dbi base\n");
> +		return PTR_ERR(hisi_pcie->reg_base);
> +	}
> +
> +	hisi_pcie->pp.dbi_base = hisi_pcie->reg_base;
> +
> +	ret = hisi_add_pcie_port(pp, pdev);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, hisi_pcie);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id hisi_pcie_of_match[] = {
> +	{.compatible = "hisilicon,hip05-pcie",},
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(of, hisi_pcie_of_match);
> +
> +static struct platform_driver hisi_pcie_driver = {
> +	.driver = {
> +		   .name = "hisi-pcie",
> +		   .of_match_table = hisi_pcie_of_match,
> +	},
> +};
> +
> +static int __init hisi_pcie_init(void)
> +{
> +	return platform_driver_probe(&hisi_pcie_driver, hisi_pcie_probe);
> +}
> +subsys_initcall(hisi_pcie_init);

Can you use module_platform_driver() or module_platform_driver_probe()
here instead of the subsys_initcall()?  No, I don't really know what
the difference between module_platform_driver() and
module_platform_driver_probe() is, sorry :)

Bjorn