On 08/29/2022, Lorenzo Pieralisi wrote:
> [+Robin, Will - please jump to DMA mask set-up]
>
> On Mon, Aug 22, 2022 at 09:47:01PM +0300, Serge Semin wrote:
> > Baikal-T1 SoC is equipped with DWC PCIe v4.60a host controller. It can be
> > trained to work up to Gen.3 speed over up to x4 lanes. The host controller
> > is attached to the DW PCIe 3.0 PCS via the PIPE-4 interface, which in its
> > turn is connected to the DWC 10G PHY. The whole system is supposed to be
> > fed up with four clock sources: DBI peripheral clock, AXI application
> > clocks and external PHY/core reference clock generating the 100MHz signal.
> > In addition to that the platform provide a way to reset each part of the
> > controller: sticky/non-sticky bits, host controller core, PIPE interface,
> > PCS/PHY and Hot/Power reset signal. The driver also provides a way to
> > handle the GPIO-based PERST# signal.
> >
> > Note due to the Baikal-T1 MMIO peculiarity we have to implement the DBI
> > interface accessors which make sure the IO operations are dword-aligned.
> >
> > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> >
> > ---
> >
> > Changelog v2:
> > - Rename 'syscon' property to 'baikal,bt1-syscon'.
> >
> > Changelog v3:
> > - Use the clocks/resets handlers defined in the DW PCIe core descriptor.
> > (@Rob)
> > - Redefine PCI host bridge config space accessors with the generic
> > pci_generic_config_read32() and pci_generic_config_write32() methods.
> > (@Rob)
> >
> > Changelog v4:
> > - Drop PCIBIOS_* macros usage. (@Rob)
> > - Add "static const" to the dw_pcie_ops and dw_pcie_host_ops structure
> > instances. (@Bjorn)
> > - Rename bt1_pcie_dw_ops to bt1_pcie_ops. (@Bjorn)
> > - Rename bt1_pcie_ops to bt1_pci_ops. (@Bjorn)
> > - Use start_link/stop_link suffixes in the corresponding callbacks.
> > (@Bjorn)
> > - Change the get_res() method suffix to being get_resources(). (@Bjorn)
> > - Change *_{add,del}_dw_port() method to *_{add,del}_port(). (@Bjorn)
> > - Drop dma_coerce_mask_and_coherent() applied to the PCI host bridge
> > kernel device instance. (@Bjorn)
> > - Add the comment above the dma_set_mask_and_coherent() method usage
> > regarding the controller eDMA feature. (@Bjorn)
> > - Fix the comment above the core reset controls assertion. (@Bjorn)
> > - Replace delays and timeout numeric literals with macros. (@Bjorn)
> > ---
> > drivers/pci/controller/dwc/Kconfig | 9 +
> > drivers/pci/controller/dwc/Makefile | 1 +
> > drivers/pci/controller/dwc/pcie-bt1.c | 653 ++++++++++++++++++++++++++
> > 3 files changed, 663 insertions(+)
> > create mode 100644 drivers/pci/controller/dwc/pcie-bt1.c
> >
> > diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> > index 62ce3abf0f19..771b8b146623 100644
> > --- a/drivers/pci/controller/dwc/Kconfig
> > +++ b/drivers/pci/controller/dwc/Kconfig
> > @@ -222,6 +222,15 @@ config PCIE_ARTPEC6_EP
> > Enables support for the PCIe controller in the ARTPEC-6 SoC to work in
> > endpoint mode. This uses the DesignWare core.
> >
> > +config PCIE_BT1
> > + tristate "Baikal-T1 PCIe controller"
> > + depends on MIPS_BAIKAL_T1 || COMPILE_TEST
> > + depends on PCI_MSI_IRQ_DOMAIN
> > + select PCIE_DW_HOST
> > + help
> > + Enables support for the PCIe controller in the Baikal-T1 SoC to work
> > + in host mode. It's based on the Synopsys DWC PCIe v4.60a IP-core.
> > +
> > config PCIE_ROCKCHIP_DW_HOST
> > bool "Rockchip DesignWare PCIe controller"
> > select PCIE_DW
> > diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> > index 8ba7b67f5e50..bf5c311875a1 100644
> > --- a/drivers/pci/controller/dwc/Makefile
> > +++ b/drivers/pci/controller/dwc/Makefile
> > @@ -3,6 +3,7 @@ obj-$(CONFIG_PCIE_DW) += pcie-designware.o
> > obj-$(CONFIG_PCIE_DW_HOST) += pcie-designware-host.o
> > obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
> > obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
> > +obj-$(CONFIG_PCIE_BT1) += pcie-bt1.o
> > obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
> > obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
> > obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
> > diff --git a/drivers/pci/controller/dwc/pcie-bt1.c b/drivers/pci/controller/dwc/pcie-bt1.c
> > new file mode 100644
> > index 000000000000..86b230575ddc
> > --- /dev/null
> > +++ b/drivers/pci/controller/dwc/pcie-bt1.c
> > @@ -0,0 +1,653 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2021 BAIKAL ELECTRONICS, JSC
> > + *
> > + * Authors:
> > + * Vadim Vlasov <Vadim.Vlasov@xxxxxxxxxxxxxxxxxxxx>
> > + * Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> > + *
> > + * Baikal-T1 PCIe controller driver
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bits.h>
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/module.h>
> > +#include <linux/pci.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +#include <linux/reset.h>
> > +#include <linux/types.h>
> > +
> > +#include "pcie-designware.h"
> > +
> > +/* Baikal-T1 System CCU control registers */
> > +#define BT1_CCU_PCIE_CLKC 0x140
> > +#define BT1_CCU_PCIE_REQ_PCS_CLK BIT(16)
> > +#define BT1_CCU_PCIE_REQ_MAC_CLK BIT(17)
> > +#define BT1_CCU_PCIE_REQ_PIPE_CLK BIT(18)
> > +
> > +#define BT1_CCU_PCIE_RSTC 0x144
> > +#define BT1_CCU_PCIE_REQ_LINK_RST BIT(13)
> > +#define BT1_CCU_PCIE_REQ_SMLH_RST BIT(14)
> > +#define BT1_CCU_PCIE_REQ_PHY_RST BIT(16)
> > +#define BT1_CCU_PCIE_REQ_CORE_RST BIT(24)
> > +#define BT1_CCU_PCIE_REQ_STICKY_RST BIT(26)
> > +#define BT1_CCU_PCIE_REQ_NSTICKY_RST BIT(27)
> > +
> > +#define BT1_CCU_PCIE_PMSC 0x148
> > +#define BT1_CCU_PCIE_LTSSM_STATE_MASK GENMASK(5, 0)
> > +#define BT1_CCU_PCIE_LTSSM_DET_QUIET 0x00
> > +#define BT1_CCU_PCIE_LTSSM_DET_ACT 0x01
> > +#define BT1_CCU_PCIE_LTSSM_POLL_ACT 0x02
> > +#define BT1_CCU_PCIE_LTSSM_POLL_COMP 0x03
> > +#define BT1_CCU_PCIE_LTSSM_POLL_CONF 0x04
> > +#define BT1_CCU_PCIE_LTSSM_PRE_DET_QUIET 0x05
> > +#define BT1_CCU_PCIE_LTSSM_DET_WAIT 0x06
> > +#define BT1_CCU_PCIE_LTSSM_CFG_LNKWD_START 0x07
> > +#define BT1_CCU_PCIE_LTSSM_CFG_LNKWD_ACEPT 0x08
> > +#define BT1_CCU_PCIE_LTSSM_CFG_LNNUM_WAIT 0x09
> > +#define BT1_CCU_PCIE_LTSSM_CFG_LNNUM_ACEPT 0x0a
> > +#define BT1_CCU_PCIE_LTSSM_CFG_COMPLETE 0x0b
> > +#define BT1_CCU_PCIE_LTSSM_CFG_IDLE 0x0c
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_LOCK 0x0d
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_SPEED 0x0e
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_RCVRCFG 0x0f
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_IDLE 0x10
> > +#define BT1_CCU_PCIE_LTSSM_L0 0x11
> > +#define BT1_CCU_PCIE_LTSSM_L0S 0x12
> > +#define BT1_CCU_PCIE_LTSSM_L123_SEND_IDLE 0x13
> > +#define BT1_CCU_PCIE_LTSSM_L1_IDLE 0x14
> > +#define BT1_CCU_PCIE_LTSSM_L2_IDLE 0x15
> > +#define BT1_CCU_PCIE_LTSSM_L2_WAKE 0x16
> > +#define BT1_CCU_PCIE_LTSSM_DIS_ENTRY 0x17
> > +#define BT1_CCU_PCIE_LTSSM_DIS_IDLE 0x18
> > +#define BT1_CCU_PCIE_LTSSM_DISABLE 0x19
> > +#define BT1_CCU_PCIE_LTSSM_LPBK_ENTRY 0x1a
> > +#define BT1_CCU_PCIE_LTSSM_LPBK_ACTIVE 0x1b
> > +#define BT1_CCU_PCIE_LTSSM_LPBK_EXIT 0x1c
> > +#define BT1_CCU_PCIE_LTSSM_LPBK_EXIT_TOUT 0x1d
> > +#define BT1_CCU_PCIE_LTSSM_HOT_RST_ENTRY 0x1e
> > +#define BT1_CCU_PCIE_LTSSM_HOT_RST 0x1f
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_EQ0 0x20
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_EQ1 0x21
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_EQ2 0x22
> > +#define BT1_CCU_PCIE_LTSSM_RCVR_EQ3 0x23
>
> You could make this an enum and define only the states
> that are actually used.
>
> [...]
>
> > +
> > +/* Generic Baikal-T1 PCIe interface resources */
> > +#define BT1_PCIE_NUM_APP_CLKS ARRAY_SIZE(bt1_pcie_app_clks)
> > +#define BT1_PCIE_NUM_CORE_CLKS ARRAY_SIZE(bt1_pcie_core_clks)
> > +#define BT1_PCIE_NUM_APP_RSTS ARRAY_SIZE(bt1_pcie_app_rsts)
> > +#define BT1_PCIE_NUM_CORE_RSTS ARRAY_SIZE(bt1_pcie_core_rsts)
> > +
> > +/* PCIe bus setup delays and timeouts */
> > +#define BT1_PCIE_RST_DELAY_MS 100
> > +#define BT1_PCIE_RUN_DELAY_US 100
> > +#define BT1_PCIE_REQ_DELAY_US 1
> > +#define BT1_PCIE_REQ_TIMEOUT_US 1000
> > +#define BT1_PCIE_LNK_DELAY_US 1000
> > +#define BT1_PCIE_LNK_TIMEOUT_US 1000000
> > +
> > +static const enum dw_pcie_app_clk bt1_pcie_app_clks[] = {
> > + DW_PCIE_DBI_CLK, DW_PCIE_MSTR_CLK, DW_PCIE_SLV_CLK,
> > +};
> > +
> > +static const enum dw_pcie_core_clk bt1_pcie_core_clks[] = {
> > + DW_PCIE_REF_CLK,
> > +};
> > +
> > +static const enum dw_pcie_app_rst bt1_pcie_app_rsts[] = {
> > + DW_PCIE_MSTR_RST, DW_PCIE_SLV_RST,
> > +};
> > +
> > +static const enum dw_pcie_core_rst bt1_pcie_core_rsts[] = {
> > + DW_PCIE_NON_STICKY_RST, DW_PCIE_STICKY_RST, DW_PCIE_CORE_RST,
> > + DW_PCIE_PIPE_RST, DW_PCIE_PHY_RST, DW_PCIE_HOT_RST, DW_PCIE_PWR_RST,
> > +};
>
> I wonder whether we could allocate the rst/clks in DWC dynamically,
> by using these configuration arrays.
>
> > +
> > +struct bt1_pcie {
> > + struct dw_pcie dw;
> > + struct platform_device *pdev;
> > + struct regmap *sys_regs;
> > +};
> > +#define to_bt1_pcie(_dw) container_of(_dw, struct bt1_pcie, dw)
> > +
> > +/*
> > + * Baikal-T1 MMIO space must be read/written by the dword-aligned
> > + * instructions. Note the methods are optimized to have the dword operations
> > + * performed with minimum overhead as the most frequently used ones.
> > + */
> > +static int bt1_pcie_read_mmio(void __iomem *addr, int size, u32 *val)
> > +{
> > + unsigned int ofs = (uintptr_t)addr & 0x3;
> > +
> > + if (!IS_ALIGNED((uintptr_t)addr, size))
> > + return -EINVAL;
> > +
> > + *val = readl(addr - ofs) >> ofs * BITS_PER_BYTE;
>
> Is it always safe to read more than requested ?
>
> > + if (size == 4) {
> > + return 0;
> > + } else if (size == 2) {
> > + *val &= 0xffff;
> > + return 0;
> > + } else if (size == 1) {
> > + *val &= 0xff;
> > + return 0;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int bt1_pcie_write_mmio(void __iomem *addr, int size, u32 val)
> > +{
> > + unsigned int ofs = (uintptr_t)addr & 0x3;
> > + u32 tmp, mask;
> > +
> > + if (!IS_ALIGNED((uintptr_t)addr, size))
> > + return -EINVAL;
> > +
> > + if (size == 4) {
> > + writel(val, addr);
> > + return 0;
> > + } else if (size == 2 || size == 1) {
> > + mask = GENMASK(size * BITS_PER_BYTE - 1, 0);
> > + tmp = readl(addr - ofs) & ~(mask << ofs * BITS_PER_BYTE);
> > + tmp |= (val & mask) << ofs * BITS_PER_BYTE;
> > + writel(tmp, addr - ofs);
> > + return 0;
> > + }
>
> Same question read/modify/write, is it always safe to do it
> regardless of size ?
>
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static u32 bt1_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base, u32 reg,
> > + size_t size)
> > +{
> > + int ret;
> > + u32 val;
> > +
> > + ret = bt1_pcie_read_mmio(base + reg, size, &val);
> > + if (ret) {
> > + dev_err(pci->dev, "Read DBI address failed\n");
> > + return ~0U;
>
> Is this a special magic value the DWC core is expecting ?
>
> Does it clash with a _valid_ return value ?
>
> > + }
> > +
> > + return val;
> > +}
> > +
> > +static void bt1_pcie_write_dbi(struct dw_pcie *pci, void __iomem *base, u32 reg,
> > + size_t size, u32 val)
> > +{
> > + int ret;
> > +
> > + ret = bt1_pcie_write_mmio(base + reg, size, val);
> > + if (ret)
> > + dev_err(pci->dev, "Write DBI address failed\n");
> > +}
> > +
> > +static void bt1_pcie_write_dbi2(struct dw_pcie *pci, void __iomem *base, u32 reg,
> > + size_t size, u32 val)
> > +{
> > + struct bt1_pcie *btpci = to_bt1_pcie(pci);
> > + int ret;
> > +
> > + regmap_update_bits(btpci->sys_regs, BT1_CCU_PCIE_GENC,
> > + BT1_CCU_PCIE_DBI2_MODE, BT1_CCU_PCIE_DBI2_MODE);
> > +
> > + ret = bt1_pcie_write_mmio(base + reg, size, val);
> > + if (ret)
> > + dev_err(pci->dev, "Write DBI2 address failed\n");
> > +
> > + regmap_update_bits(btpci->sys_regs, BT1_CCU_PCIE_GENC,
> > + BT1_CCU_PCIE_DBI2_MODE, 0);
>
> IIUC the regmap_update_bits() set up decoding for DBI2. Hopefully the
> DBI/DBI2 writes are sequentialized, this is a question valid also
> for other DWC controllers.
>
> What I want to say is, the regmap update in this function sets the
> DWC HW in a way that can decode DBI2 (please correct me if I am wrong),
> between the two _update_bits() no DBI access should happen because
> it just would not work.
>
> It is a question.
>
> > +static int bt1_pcie_host_init(struct dw_pcie_rp *pp)
> > +{
> > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > + struct bt1_pcie *btpci = to_bt1_pcie(pci);
> > + int ret;
> > +
> > + ret = bt1_pcie_get_resources(btpci);
> > + if (ret)
> > + return ret;
> > +
> > + bt1_pcie_full_stop_bus(btpci, true);
> > +
> > + return bt1_pcie_cold_start_bus(btpci);
> > +}
> > +
> > +static void bt1_pcie_host_deinit(struct dw_pcie_rp *pp)
> > +{
> > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > + struct bt1_pcie *btpci = to_bt1_pcie(pci);
> > +
> > + bt1_pcie_full_stop_bus(btpci, false);
> > +}
> > +
> > +static const struct dw_pcie_host_ops bt1_pcie_host_ops = {
> > + .host_init = bt1_pcie_host_init,
> > + .host_deinit = bt1_pcie_host_deinit,
> > +};
> > +
> > +static struct bt1_pcie *bt1_pcie_create_data(struct platform_device *pdev)
> > +{
> > + struct bt1_pcie *btpci;
> > +
> > + btpci = devm_kzalloc(&pdev->dev, sizeof(*btpci), GFP_KERNEL);
> > + if (!btpci)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + btpci->pdev = pdev;
> > +
> > + platform_set_drvdata(pdev, btpci);
> > +
> > + return btpci;
> > +}
> > +
> > +static int bt1_pcie_add_port(struct bt1_pcie *btpci)
> > +{
> > + struct device *dev = &btpci->pdev->dev;
> > + int ret;
> > +
> > + /*
> > + * DW PCIe Root Port controller is equipped with eDMA capable of
> > + * working with the 64-bit memory addresses.
> > + */
> > + ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
> > + if (ret)
> > + return ret;
>
> Is this the right place to set the DMA mask for the host controller
> embedded DMA controller (actually, the dev pointer is the _host_
> controller device) ?
>
> How this is going to play when combined with:
>
> https://lore.kernel.org/linux-pci/1e63a581-14ae-b4b5-a5bf-ca8f09c33af6@xxxxxxx
>
> It is getting a bit confusing. I believe the code in the link
> above sets the mask so that through the DMA API we are capable
> of getting an MSI doorbell virtual address whose physical address
> can be addressed by the endpoint; this through the DMA API.
>
> This patch is setting the DMA mask for a different reason, namely
> setting the host controller embedded DMA controller addressing
> capabilities.
>
> AFAICS - both approaches set the mask for the same device - now
> the question is about which one is legitimate and how to handle
> the other.
Since the mask is being set before calling dw_pcie_host_init() and the
msi_host_init op is not set, setting the mask here won't have any affect due to
the fact that dw_pcie_msi_host_init() unconditionally sets the DMA mask. AFAIK,
you don't technically need a 64-bit address, right? If your platform disables
32-bit allocations, then you'll need to set the MSI capabilities flag to
support a 64-bit allocation for when the 32-bit allocation fails in the host
controller driver.
Here is how I'm doing that with the Exynos PCIe driver during probe before
calling dw_pcie_host_init():
dw_pcie_dbi_ro_wr_en(exynos_pcie->pci);
offset = dw_pcie_find_capability(exynos_pcie->pci, PCI_CAP_ID_MSI);
cap = dw_pcie_readw_dbi(exynos_pcie->pci, offset + PCI_MSI_FLAGS);
/* Enable MSI with 64-bit support */
cap |= PCI_MSI_FLAGS_ENABLE | PCI_MSI_FLAGS_64BIT;
dw_pcie_writew_dbi(exynos_pcie->pci, offset + PCI_MSI_FLAGS, cap);
dw_pcie_dbi_ro_wr_dis(exynos_pcie->pci);
I hope that helps!
Regards,
Will
>
> > +
> > + btpci->dw.version = DW_PCIE_VER_460A;
> > + btpci->dw.dev = dev;
> > + btpci->dw.ops = &bt1_pcie_ops;
> > +
> > + btpci->dw.pp.num_vectors = MAX_MSI_IRQS;
> > + btpci->dw.pp.ops = &bt1_pcie_host_ops;
> > +
> > + dw_pcie_cap_set(&btpci->dw, REQ_RES);
> > +
> > + ret = dw_pcie_host_init(&btpci->dw.pp);
> > + if (ret)
> > + dev_err_probe(dev, ret, "Failed to initialize DWC PCIe host\n");
> > +
> > + return ret;
> > +}
> > +
> > +static void bt1_pcie_del_port(struct bt1_pcie *btpci)
> > +{
> > + dw_pcie_host_deinit(&btpci->dw.pp);
> > +}
> > +
> > +static int bt1_pcie_probe(struct platform_device *pdev)
> > +{
> > + struct bt1_pcie *btpci;
> > +
> > + btpci = bt1_pcie_create_data(pdev);
>
> Do we really need a function for that ? I am not too
> bothered but I think it is overkill.
>
> Thanks,
> Lorenzo
>
> > + if (IS_ERR(btpci))
> > + return PTR_ERR(btpci);
> > +
> > + return bt1_pcie_add_port(btpci);
> > +}
> > +
> > +static int bt1_pcie_remove(struct platform_device *pdev)
> > +{
> > + struct bt1_pcie *btpci = platform_get_drvdata(pdev);
> > +
> > + bt1_pcie_del_port(btpci);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id bt1_pcie_of_match[] = {
> > + { .compatible = "baikal,bt1-pcie" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, bt1_pcie_of_match);
> > +
> > +static struct platform_driver bt1_pcie_driver = {
> > + .probe = bt1_pcie_probe,
> > + .remove = bt1_pcie_remove,
> > + .driver = {
> > + .name = "bt1-pcie",
> > + .of_match_table = bt1_pcie_of_match,
> > + },
> > +};
> > +module_platform_driver(bt1_pcie_driver);
> > +
> > +MODULE_AUTHOR("Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("Baikal-T1 PCIe driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.35.1
> >
