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Date: Tue, 16 Oct 2012 13:23:38 +0900
From: Takao Indoh <indou.takao@...fujitsu.com>
To: yinghai@...nel.org
CC: martin.wilck@...fujitsu.com, linux-pci@...r.kernel.org,
x86@...nel.org, kexec@...ts.infradead.org,
linux-kernel@...r.kernel.org, hbabu@...ibm.com,
andi@...stfloor.org, ddutile@...hat.com,
ishii.hironobu@...fujitsu.com, hpa@...or.com, bhelgaas@...gle.com,
tglx@...utronix.de, mingo@...hat.com, vgoyal@...hat.com,
khalid@...ehiking.org
Subject: Re: [PATCH v4 1/2] x86, pci: Reset PCIe devices at boot time
(2012/10/16 3:36), Yinghai Lu wrote:
> On Mon, Oct 15, 2012 at 12:00 AM, Takao Indoh
> <indou.takao@...fujitsu.com> wrote:
>> This patch resets PCIe devices at boot time by hot reset when
>> "reset_devices" is specified.
>
> how about pci devices that domain_nr is not zero ?
This patch does not support multiple domains yet.
>>
>> Signed-off-by: Takao Indoh <indou.takao@...fujitsu.com>
>> ---
>> arch/x86/include/asm/pci-direct.h | 1
>> arch/x86/kernel/setup.c | 3
>> arch/x86/pci/early.c | 344 ++++++++++++++++++++++++++++
>> include/linux/pci.h | 2
>> init/main.c | 4
>> 5 files changed, 352 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pci-direct.h b/arch/x86/include/asm/pci-direct.h
>> index b1e7a45..de30db2 100644
>> --- a/arch/x86/include/asm/pci-direct.h
>> +++ b/arch/x86/include/asm/pci-direct.h
>> @@ -18,4 +18,5 @@ extern int early_pci_allowed(void);
>> extern unsigned int pci_early_dump_regs;
>> extern void early_dump_pci_device(u8 bus, u8 slot, u8 func);
>> extern void early_dump_pci_devices(void);
>> +extern void early_reset_pcie_devices(void);
>> #endif /* _ASM_X86_PCI_DIRECT_H */
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index a2bb18e..73d3425 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -987,6 +987,9 @@ void __init setup_arch(char **cmdline_p)
>> generic_apic_probe();
>>
>> early_quirks();
>> +#ifdef CONFIG_PCI
>> + early_reset_pcie_devices();
>> +#endif
>>
>> /*
>> * Read APIC and some other early information from ACPI tables.
>> diff --git a/arch/x86/pci/early.c b/arch/x86/pci/early.c
>> index d1067d5..683b30f 100644
>> --- a/arch/x86/pci/early.c
>> +++ b/arch/x86/pci/early.c
>> @@ -1,5 +1,6 @@
>> #include <linux/kernel.h>
>> #include <linux/pci.h>
>> +#include <linux/bootmem.h>
>> #include <asm/pci-direct.h>
>> #include <asm/io.h>
>> #include <asm/pci_x86.h>
>> @@ -109,3 +110,346 @@ void early_dump_pci_devices(void)
>> }
>> }
>> }
>> +
>> +#define PCI_EXP_SAVE_REGS 7
>> +#define pcie_cap_has_devctl(type, flags) 1
>> +#define pcie_cap_has_lnkctl(type, flags) \
>> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
>> + (type == PCI_EXP_TYPE_ROOT_PORT || \
>> + type == PCI_EXP_TYPE_ENDPOINT || \
>> + type == PCI_EXP_TYPE_LEG_END))
>> +#define pcie_cap_has_sltctl(type, flags) \
>> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
>> + ((type == PCI_EXP_TYPE_ROOT_PORT) || \
>> + (type == PCI_EXP_TYPE_DOWNSTREAM && \
>> + (flags & PCI_EXP_FLAGS_SLOT))))
>> +#define pcie_cap_has_rtctl(type, flags) \
>> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
>> + (type == PCI_EXP_TYPE_ROOT_PORT || \
>> + type == PCI_EXP_TYPE_RC_EC))
>> +
>> +struct save_config {
>> + u32 pci[16];
>> + u16 pcie[PCI_EXP_SAVE_REGS];
>> +};
>> +
>> +struct pcie_dev {
>> + int cap; /* position of PCI Express capability */
>> + int flags; /* PCI_EXP_FLAGS */
>> + struct save_config save; /* saved configration register */
>> +};
>> +
>> +struct pcie_port {
>> + struct list_head dev;
>> + u8 secondary;
>> + struct pcie_dev child[PCI_MAX_FUNCTIONS];
>> +};
>> +
>> +static LIST_HEAD(device_list);
>> +static void __init pci_udelay(int loops)
>> +{
>> + while (loops--) {
>> + /* Approximately 1 us */
>> + native_io_delay();
>> + }
>> +}
>> +
>> +/* Derived from drivers/pci/pci.c */
>> +#define PCI_FIND_CAP_TTL 48
>> +static int __init __pci_find_next_cap_ttl(u8 bus, u8 slot, u8 func,
>> + u8 pos, int cap, int *ttl)
>> +{
>> + u8 id;
>> +
>> + while ((*ttl)--) {
>> + pos = read_pci_config_byte(bus, slot, func, pos);
>> + if (pos < 0x40)
>> + break;
>> + pos &= ~3;
>> + id = read_pci_config_byte(bus, slot, func,
>> + pos + PCI_CAP_LIST_ID);
>> + if (id == 0xff)
>> + break;
>> + if (id == cap)
>> + return pos;
>> + pos += PCI_CAP_LIST_NEXT;
>> + }
>> + return 0;
>> +}
>> +
>> +static int __init __pci_find_next_cap(u8 bus, u8 slot, u8 func, u8 pos, int cap)
>> +{
>> + int ttl = PCI_FIND_CAP_TTL;
>> +
>> + return __pci_find_next_cap_ttl(bus, slot, func, pos, cap, &ttl);
>> +}
>> +
>> +static int __init __pci_bus_find_cap_start(u8 bus, u8 slot, u8 func,
>> + u8 hdr_type)
>> +{
>> + u16 status;
>> +
>> + status = read_pci_config_16(bus, slot, func, PCI_STATUS);
>> + if (!(status & PCI_STATUS_CAP_LIST))
>> + return 0;
>> +
>> + switch (hdr_type) {
>> + case PCI_HEADER_TYPE_NORMAL:
>> + case PCI_HEADER_TYPE_BRIDGE:
>> + return PCI_CAPABILITY_LIST;
>> + case PCI_HEADER_TYPE_CARDBUS:
>> + return PCI_CB_CAPABILITY_LIST;
>> + default:
>> + return 0;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int __init early_pci_find_capability(u8 bus, u8 slot, u8 func, int cap)
>> +{
>> + int pos;
>> + u8 type = read_pci_config_byte(bus, slot, func, PCI_HEADER_TYPE);
>> +
>> + pos = __pci_bus_find_cap_start(bus, slot, func, type & 0x7f);
>> + if (pos)
>> + pos = __pci_find_next_cap(bus, slot, func, pos, cap);
>> +
>> + return pos;
>> +}
>> +
>> +static void __init do_reset(u8 bus, u8 slot, u8 func)
>> +{
>> + u16 ctrl;
>> +
>> + printk(KERN_INFO "pci 0000:%02x:%02x.%d reset\n", bus, slot, func);
>> +
>> + /* Assert Secondary Bus Reset */
>> + ctrl = read_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL);
>> + ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
>> + write_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL, ctrl);
>> +
>> + /*
>> + * PCIe spec requires software to ensure a minimum reset duration
>> + * (Trst == 1ms). We have here 5ms safety margin because pci_udelay is
>> + * not precise.
>> + */
>> + pci_udelay(5000);
>> +
>> + /* De-assert Secondary Bus Reset */
>> + ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
>> + write_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL, ctrl);
>> +}
>> +
>> +static void __init save_state(unsigned bus, unsigned slot, unsigned func,
>> + struct pcie_dev *dev)
>> +{
>> + int i;
>> + int pcie, flags, pcie_type;
>> + struct save_config *save;
>> +
>> + pcie = dev->cap;
>> + flags = dev->flags;
>> + pcie_type = (flags & PCI_EXP_FLAGS_TYPE) >> 4;
>> + save = &dev->save;
>> +
>> + printk(KERN_INFO "pci 0000:%02x:%02x.%d save state\n", bus, slot, func);
>> +
>> + for (i = 0; i < 16; i++)
>> + save->pci[i] = read_pci_config(bus, slot, func, i * 4);
>> + i = 0;
>> + if (pcie_cap_has_devctl(pcie_type, flags))
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_DEVCTL);
>> + if (pcie_cap_has_lnkctl(pcie_type, flags))
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_LNKCTL);
>> + if (pcie_cap_has_sltctl(pcie_type, flags))
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_SLTCTL);
>> + if (pcie_cap_has_rtctl(pcie_type, flags))
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_RTCTL);
>> +
>> + if ((flags & PCI_EXP_FLAGS_VERS) >= 2) {
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_DEVCTL2);
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_LNKCTL2);
>> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_SLTCTL2);
>> + }
>> +}
>> +
>> +static void __init restore_state(unsigned bus, unsigned slot, unsigned func,
>> + struct pcie_dev *dev)
>> +{
>> + int i = 0;
>> + int pcie, flags, pcie_type;
>> + struct save_config *save;
>> +
>> + pcie = dev->cap;
>> + flags = dev->flags;
>> + pcie_type = (flags & PCI_EXP_FLAGS_TYPE) >> 4;
>> + save = &dev->save;
>> +
>> + printk(KERN_INFO "pci 0000:%02x:%02x.%d restore state\n",
>> + bus, slot, func);
>> +
>> + if (pcie_cap_has_devctl(pcie_type, flags))
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_DEVCTL, save->pcie[i++]);
>> + if (pcie_cap_has_lnkctl(pcie_type, flags))
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_LNKCTL, save->pcie[i++]);
>> + if (pcie_cap_has_sltctl(pcie_type, flags))
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_SLTCTL, save->pcie[i++]);
>> + if (pcie_cap_has_rtctl(pcie_type, flags))
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_RTCTL, save->pcie[i++]);
>> +
>> + if ((flags & PCI_EXP_FLAGS_VERS) >= 2) {
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_DEVCTL2, save->pcie[i++]);
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_LNKCTL2, save->pcie[i++]);
>> + write_pci_config_16(bus, slot, func,
>> + pcie + PCI_EXP_SLTCTL2, save->pcie[i++]);
>> + }
>> +
>> + for (i = 15; i >= 0; i--)
>> + write_pci_config(bus, slot, func, i * 4, save->pci[i]);
>> +}
>
> do you have to pass bus/slot/func and use read/pci_config directly ?
>
> I had one patchset that use dummy pci device and reuse existing late quirk code
> in early_quirk to do usb handoff early.
>
> please check
>
> git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git
> for-x86-early-quirk-usb
>
> 678a023: x86: usb handoff in early_quirk
> 2d418d8: pci, usb: Make usb handoff func all take base remapping
> d9bd1ad: x86, pci: add dummy pci device for early stage
> de38757: x86: early_quirk check all bus/dev/func in domain 0
> 325cc7a: make msleep to do mdelay before scheduler is running
> eec78a4: x86: set percpu cpu_info lpj to default
> 52ebec4: x86, pci: early dump skip device the same way as later probe code
>
> if that could help.
> you may reuse some later functions that take pci_dev as parameters.
d9bd1ad looks very useful for my patch. Thanks for the information.
What is the status of this patch? Already got in tip tree or
somewhere?
> also mdelay should work early...
mdelay does not work in early.c as far as I tested. Maybe
it works after calibration.
> and use early_quirk instead add another calling in setup.c
I think this reset code should not be added to early_quirk.
In my understanding "quirk" is used to avoid problems of specific
hardware.
Thanks,
Takao Indoh
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