Re: [PATCH v1 3/4] PCI: brcmstb: Add panic/die handler to RC driver

Jim Quinlan
2021-05-25T21:06:07Z

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On Tue, May 25, 2021 at 4:40 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Tue, Apr 27, 2021 at 01:51:38PM -0400, Jim Quinlan wrote:
> > Whereas most PCIe HW returns 0xffffffff on illegal accesses and the like,
> > by default Broadcom's STB PCIe controller effects an abort. This simple
> > handler determines if the PCIe controller was the cause of the abort and if
> > so, prints out diagnostic info.
> >
> > Example output:
> > brcm-pcie 8b20000.pcie: Error: Mem Acc: 32bit, Read, @0x38000000
> > brcm-pcie 8b20000.pcie: Type: TO=0 Abt=0 UnspReq=1 AccDsble=0 BadAddr=0
>
> What happens to the driver that performed the illegal access?

The entire system dies from the abort. Some customers elect to do a
fixup in the abort handler but we admonish them to fix the root cause.
With these patches we at least get immediate information about the
access that caused the abort.
>
>
> Does this mean that errors that are recoverable on other hardware (by
> noticing the 0xffffffff and checking for error) are fatal on the
> Broadcom STB?

Yes. For example, I have an old Rocketport RP2 card I sometimes use
for testing. On a Broadcom STB it dies when the rp2 probe does a
read after calling rp2_reset_asic(). On an x86, 0xffffffff is
returned on this read and all is well.

I don't think there is any PCIe spec that mandates an access error
returns 0xffffffff. Some of our SOCs have a new feature where we can
return the 0xffffffff instead of getting an abort. We will allow the
customer to turn this on if they ask for it, but for the time being we
prefer an abort as many drivers do not check for 0xffffffff.

Regards,
Jim Quinlan
Broadcom STB
>
>
> > Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
> > Acked-by: Florian Fainelli <f.fainelli@gmail.com>
> > ---
> > drivers/pci/controller/pcie-brcmstb.c | 122 ++++++++++++++++++++++++++
> > 1 file changed, 122 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index 3b6a62dd2e72..d3af8d84f0d6 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -12,11 +12,13 @@
> > #include <linux/ioport.h>
> > #include <linux/irqchip/chained_irq.h>
> > #include <linux/irqdomain.h>
> > +#include <linux/kdebug.h>
> > #include <linux/kernel.h>
> > #include <linux/list.h>
> > #include <linux/log2.h>
> > #include <linux/module.h>
> > #include <linux/msi.h>
> > +#include <linux/notifier.h>
> > #include <linux/of_address.h>
> > #include <linux/of_irq.h>
> > #include <linux/of_pci.h>
> > @@ -184,6 +186,39 @@
> > #define PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_MASK 0x1
> > #define PCIE_DVT_PMU_PCIE_PHY_CTRL_DAST_PWRDN_SHIFT 0x0
> >
> > +/* Error report regiseters */
> > +#define PCIE_OUTB_ERR_TREAT 0x6000
> > +#define PCIE_OUTB_ERR_TREAT_CONFIG_MASK 0x1
> > +#define PCIE_OUTB_ERR_TREAT_MEM_MASK 0x2
> > +#define PCIE_OUTB_ERR_VALID 0x6004
> > +#define PCIE_OUTB_ERR_CLEAR 0x6008
> > +#define PCIE_OUTB_ERR_ACC_INFO 0x600c
> > +#define PCIE_OUTB_ERR_ACC_INFO_CFG_ERR_MASK 0x01
> > +#define PCIE_OUTB_ERR_ACC_INFO_MEM_ERR_MASK 0x02
> > +#define PCIE_OUTB_ERR_ACC_INFO_TYPE_64_MASK 0x04
> > +#define PCIE_OUTB_ERR_ACC_INFO_DIR_WRITE_MASK 0x10
> > +#define PCIE_OUTB_ERR_ACC_INFO_BYTE_LANES_MASK 0xff00
> > +#define PCIE_OUTB_ERR_ACC_ADDR 0x6010
> > +#define PCIE_OUTB_ERR_ACC_ADDR_BUS_MASK 0xff00000
> > +#define PCIE_OUTB_ERR_ACC_ADDR_DEV_MASK 0xf8000
> > +#define PCIE_OUTB_ERR_ACC_ADDR_FUNC_MASK 0x7000
> > +#define PCIE_OUTB_ERR_ACC_ADDR_REG_MASK 0xfff
> > +#define PCIE_OUTB_ERR_CFG_CAUSE 0x6014
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_TIMEOUT_MASK 0x40
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_ABORT_MASK 0x20
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_UNSUPP_REQ_MASK 0x10
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_ACC_TIMEOUT_MASK 0x4
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_ACC_DISABLED_MASK 0x2
> > +#define PCIE_OUTB_ERR_CFG_CAUSE_ACC_64BIT__MASK 0x1
> > +#define PCIE_OUTB_ERR_MEM_ADDR_LO 0x6018
> > +#define PCIE_OUTB_ERR_MEM_ADDR_HI 0x601c
> > +#define PCIE_OUTB_ERR_MEM_CAUSE 0x6020
> > +#define PCIE_OUTB_ERR_MEM_CAUSE_TIMEOUT_MASK 0x40
> > +#define PCIE_OUTB_ERR_MEM_CAUSE_ABORT_MASK 0x20
> > +#define PCIE_OUTB_ERR_MEM_CAUSE_UNSUPP_REQ_MASK 0x10
> > +#define PCIE_OUTB_ERR_MEM_CAUSE_ACC_DISABLED_MASK 0x2
> > +#define PCIE_OUTB_ERR_MEM_CAUSE_BAD_ADDR_MASK 0x1
> > +
> > /* Forward declarations */
> > struct brcm_pcie;
> > static inline void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32 val);
> > @@ -215,6 +250,7 @@ struct pcie_cfg_data {
> > const enum pcie_type type;
> > void (*perst_set)(struct brcm_pcie *pcie, u32 val);
> > void (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
> > + const bool has_err_report;
> > };
> >
> > static const int pcie_offsets[] = {
> > @@ -262,6 +298,7 @@ static const struct pcie_cfg_data bcm7216_cfg = {
> > .type = BCM7278,
> > .perst_set = brcm_pcie_perst_set_7278,
> > .bridge_sw_init_set = brcm_pcie_bridge_sw_init_set_7278,
> > + .has_err_report = true,
> > };
> >
> > struct brcm_msi {
> > @@ -302,8 +339,87 @@ struct brcm_pcie {
> > u32 hw_rev;
> > void (*perst_set)(struct brcm_pcie *pcie, u32 val);
> > void (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
> > + bool has_err_report;
> > + struct notifier_block die_notifier;
> > };
> >
> > +/* Dump out PCIe errors on die or panic */
> > +static int dump_pcie_error(struct notifier_block *self, unsigned long v, void *p)
> > +{
> > + const struct brcm_pcie *pcie = container_of(self, struct brcm_pcie, die_notifier);
> > + void __iomem *base = pcie->base;
> > + int i, is_cfg_err, is_mem_err, lanes;
> > + char *width_str, *direction_str, lanes_str[9];
> > + u32 info;
> > +
> > + if (readl(base + PCIE_OUTB_ERR_VALID) == 0)
> > + return NOTIFY_DONE;
> > + info = readl(base + PCIE_OUTB_ERR_ACC_INFO);
> > +
> > +
> > + is_cfg_err = !!(info & PCIE_OUTB_ERR_ACC_INFO_CFG_ERR_MASK);
> > + is_mem_err = !!(info & PCIE_OUTB_ERR_ACC_INFO_MEM_ERR_MASK);
> > + width_str = (info & PCIE_OUTB_ERR_ACC_INFO_TYPE_64_MASK) ? "64bit" : "32bit";
> > + direction_str = (info & PCIE_OUTB_ERR_ACC_INFO_DIR_WRITE_MASK) ? "Write" : "Read";
> > + lanes = FIELD_GET(PCIE_OUTB_ERR_ACC_INFO_BYTE_LANES_MASK, info);
> > + for (i = 0, lanes_str[8] = 0; i < 8; i++)
> > + lanes_str[i] = (lanes & (1 << i)) ? '1' : '0';
> > +
> > + if (is_cfg_err) {
> > + u32 cfg_addr = readl(base + PCIE_OUTB_ERR_ACC_ADDR);
> > + u32 cause = readl(base + PCIE_OUTB_ERR_CFG_CAUSE);
> > + int bus = FIELD_GET(PCIE_OUTB_ERR_ACC_ADDR_BUS_MASK, cfg_addr);
> > + int dev = FIELD_GET(PCIE_OUTB_ERR_ACC_ADDR_DEV_MASK, cfg_addr);
> > + int func = FIELD_GET(PCIE_OUTB_ERR_ACC_ADDR_FUNC_MASK, cfg_addr);
> > + int reg = FIELD_GET(PCIE_OUTB_ERR_ACC_ADDR_REG_MASK, cfg_addr);
> > +
> > + dev_err(pcie->dev, "Error: CFG Acc, %s, %s, Bus=%d, Dev=%d, Fun=%d, Reg=0x%x, lanes=%s\n",
> > + width_str, direction_str, bus, dev, func, reg, lanes_str);
> > + dev_err(pcie->dev, " Type: TO=%d Abt=%d UnsupReq=%d AccTO=%d AccDsbld=%d Acc64bit=%d\n",
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_TIMEOUT_MASK),
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_ABORT_MASK),
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_UNSUPP_REQ_MASK),
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_ACC_TIMEOUT_MASK),
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_ACC_DISABLED_MASK),
> > + !!(cause & PCIE_OUTB_ERR_CFG_CAUSE_ACC_64BIT__MASK));
> > + }
> > +
> > + if (is_mem_err) {
> > + u32 cause = readl(base + PCIE_OUTB_ERR_MEM_CAUSE);
> > + u32 lo = readl(base + PCIE_OUTB_ERR_MEM_ADDR_LO);
> > + u32 hi = readl(base + PCIE_OUTB_ERR_MEM_ADDR_HI);
> > + u64 addr = ((u64)hi << 32) | (u64)lo;
> > +
> > + dev_err(pcie->dev, "Error: Mem Acc, %s, %s, @0x%llx, lanes=%s\n",
> > + width_str, direction_str, addr, lanes_str);
> > + dev_err(pcie->dev, " Type: TO=%d Abt=%d UnsupReq=%d AccDsble=%d BadAddr=%d\n",
> > + !!(cause & PCIE_OUTB_ERR_MEM_CAUSE_TIMEOUT_MASK),
> > + !!(cause & PCIE_OUTB_ERR_MEM_CAUSE_ABORT_MASK),
> > + !!(cause & PCIE_OUTB_ERR_MEM_CAUSE_UNSUPP_REQ_MASK),
> > + !!(cause & PCIE_OUTB_ERR_MEM_CAUSE_ACC_DISABLED_MASK),
> > + !!(cause & PCIE_OUTB_ERR_MEM_CAUSE_BAD_ADDR_MASK));
> > + }
> > +
> > + /* Clear the error */
> > + writel(1, base + PCIE_OUTB_ERR_CLEAR);
> > +
> > + return NOTIFY_DONE;
> > +}
> > +
> > +static void brcm_register_die_notifiers(struct brcm_pcie *pcie)
> > +{
> > + pcie->die_notifier.notifier_call = dump_pcie_error;
> > + register_die_notifier(&pcie->die_notifier);
> > + atomic_notifier_chain_register(&panic_notifier_list, &pcie->die_notifier);
> > +}
> > +
> > +static void brcm_unregister_die_notifiers(struct brcm_pcie *pcie)
> > +{
> > + unregister_die_notifier(&pcie->die_notifier);
> > + atomic_notifier_chain_unregister(&panic_notifier_list, &pcie->die_notifier);
> > + pcie->die_notifier.notifier_call = NULL;
> > +}
> > +
> > /*
> > * This is to convert the size of the inbound "BAR" region to the
> > * non-linear values of PCIE_X_MISC_RC_BAR[123]_CONFIG_LO.SIZE
> > @@ -1216,6 +1332,8 @@ static int brcm_pcie_remove(struct platform_device *pdev)
> > struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
> >
> > pci_stop_root_bus(bridge->bus);
> > + if (pcie->has_err_report)
> > + brcm_unregister_die_notifiers(pcie);
> > pci_remove_root_bus(bridge->bus);
> > __brcm_pcie_remove(pcie);
> >
> > @@ -1255,6 +1373,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> > pcie->np = np;
> > pcie->reg_offsets = data->offsets;
> > pcie->type = data->type;
> > + pcie->has_err_report = data->has_err_report;
> > pcie->perst_set = data->perst_set;
> > pcie->bridge_sw_init_set = data->bridge_sw_init_set;
> >
> > @@ -1322,6 +1441,9 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> >
> > platform_set_drvdata(pdev, pcie);
> >
> > + if (pcie->has_err_report)
> > + brcm_register_die_notifiers(pcie);
> > +
> > return pci_host_probe(bridge);
> > fail:
> > __brcm_pcie_remove(pcie);
> > --
> > 2.17.1
> >

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