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Merge branch 'pci/controller/broadcom'

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- Add DT property "brcm,clkreq-mode" and driver support for different
  CLKREQ# modes (Jim Quinlan)

* pci/controller/broadcom:
  PCI: brcmstb: Configure HW CLKREQ# mode appropriate for downstream device
  dt-bindings: PCI: brcmstb: Add property "brcm,clkreq-mode"
This commit is contained in:
Bjorn Helgaas 2024-01-15 12:10:36 -06:00
commit 6f77f0ac5e
2 changed files with 104 additions and 10 deletions
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18
Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
View File

@ -64,6 +64,24 @@ properties:
aspm-no-l0s: true
brcm,clkreq-mode:
description: A string that determines the operating
clkreq mode of the PCIe RC HW with respect to controlling the refclk
signal. There are three different modes -- "safe", which drives the
refclk signal unconditionally and will work for all devices but does
not provide any power savings; "no-l1ss" -- which provides Clock
Power Management, L0s, and L1, but cannot provide L1 substate (L1SS)
power savings. If the downstream device connected to the RC is L1SS
capable AND the OS enables L1SS, all PCIe traffic may abruptly halt,
potentially hanging the system; "default" -- which provides L0s, L1,
and L1SS, but not compliant to provide Clock Power Management;
specifically, may not be able to meet the T_CLRon max timing of 400ns
as specified in "Dynamic Clock Control", section 3.2.5.2.2 PCI
Express Mini CEM 2.1 specification. This situation is atypical and
should happen only with older devices.
$ref: /schemas/types.yaml#/definitions/string
enum: [ safe, no-l1ss, default ]
brcm,scb-sizes:
description: u64 giving the 64bit PCIe memory
viewport size of a memory controller. There may be up to

96
drivers/pci/controller/pcie-brcmstb.c
View File

@ -48,6 +48,9 @@
#define PCIE_RC_CFG_PRIV1_LINK_CAPABILITY 0x04dc
#define PCIE_RC_CFG_PRIV1_LINK_CAPABILITY_ASPM_SUPPORT_MASK 0xc00
#define PCIE_RC_CFG_PRIV1_ROOT_CAP 0x4f8
#define PCIE_RC_CFG_PRIV1_ROOT_CAP_L1SS_MODE_MASK 0xf8
#define PCIE_RC_DL_MDIO_ADDR 0x1100
#define PCIE_RC_DL_MDIO_WR_DATA 0x1104
#define PCIE_RC_DL_MDIO_RD_DATA 0x1108
@ -121,9 +124,12 @@
#define PCIE_MISC_HARD_PCIE_HARD_DEBUG 0x4204
#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK 0x2
#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_L1SS_ENABLE_MASK 0x200000
#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK 0x08000000
#define PCIE_BMIPS_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK 0x00800000
#define PCIE_CLKREQ_MASK \
(PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK | \
PCIE_MISC_HARD_PCIE_HARD_DEBUG_L1SS_ENABLE_MASK)
#define PCIE_INTR2_CPU_BASE 0x4300
#define PCIE_MSI_INTR2_BASE 0x4500
@ -1028,13 +1034,89 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
return 0;
}
/*
* This extends the timeout period for an access to an internal bus. This
* access timeout may occur during L1SS sleep periods, even without the
* presence of a PCIe access.
*/
static void brcm_extend_rbus_timeout(struct brcm_pcie *pcie)
{
/* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
u32 timeout_us = 4000000; /* 4 seconds, our setting for L1SS */
/* Each unit in timeout register is 1/216,000,000 seconds */
writel(216 * timeout_us, pcie->base + REG_OFFSET);
}
static void brcm_config_clkreq(struct brcm_pcie *pcie)
{
static const char err_msg[] = "invalid 'brcm,clkreq-mode' DT string\n";
const char *mode = "default";
u32 clkreq_cntl;
int ret, tmp;
ret = of_property_read_string(pcie->np, "brcm,clkreq-mode", &mode);
if (ret && ret != -EINVAL) {
dev_err(pcie->dev, err_msg);
mode = "safe";
}
/* Start out assuming safe mode (both mode bits cleared) */
clkreq_cntl = readl(pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
clkreq_cntl &= ~PCIE_CLKREQ_MASK;
if (strcmp(mode, "no-l1ss") == 0) {
/*
* "no-l1ss" -- Provides Clock Power Management, L0s, and
* L1, but cannot provide L1 substate (L1SS) power
* savings. If the downstream device connected to the RC is
* L1SS capable AND the OS enables L1SS, all PCIe traffic
* may abruptly halt, potentially hanging the system.
*/
clkreq_cntl |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK;
/*
* We want to un-advertise L1 substates because if the OS
* tries to configure the controller into using L1 substate
* power savings it may fail or hang when the RC HW is in
* "no-l1ss" mode.
*/
tmp = readl(pcie->base + PCIE_RC_CFG_PRIV1_ROOT_CAP);
u32p_replace_bits(&tmp, 2, PCIE_RC_CFG_PRIV1_ROOT_CAP_L1SS_MODE_MASK);
writel(tmp, pcie->base + PCIE_RC_CFG_PRIV1_ROOT_CAP);
} else if (strcmp(mode, "default") == 0) {
/*
* "default" -- Provides L0s, L1, and L1SS, but not
* compliant to provide Clock Power Management;
* specifically, may not be able to meet the Tclron max
* timing of 400ns as specified in "Dynamic Clock Control",
* section 3.2.5.2.2 of the PCIe spec. This situation is
* atypical and should happen only with older devices.
*/
clkreq_cntl |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_L1SS_ENABLE_MASK;
brcm_extend_rbus_timeout(pcie);
} else {
/*
* "safe" -- No power savings; refclk is driven by RC
* unconditionally.
*/
if (strcmp(mode, "safe") != 0)
dev_err(pcie->dev, err_msg);
mode = "safe";
}
writel(clkreq_cntl, pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
dev_info(pcie->dev, "clkreq-mode set to %s\n", mode);
}
static int brcm_pcie_start_link(struct brcm_pcie *pcie)
{
struct device *dev = pcie->dev;
void __iomem *base = pcie->base;
u16 nlw, cls, lnksta;
bool ssc_good = false;
u32 tmp;
int ret, i;
/* Unassert the fundamental reset */
@ -1059,6 +1141,8 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
return -ENODEV;
}
brcm_config_clkreq(pcie);
if (pcie->gen)
brcm_pcie_set_gen(pcie, pcie->gen);
@ -1077,14 +1161,6 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
pci_speed_string(pcie_link_speed[cls]), nlw,
ssc_good ? "(SSC)" : "(!SSC)");
/*
* Refclk from RC should be gated with CLKREQ# input when ASPM L0s,L1
* is enabled => setting the CLKREQ_DEBUG_ENABLE field to 1.
*/
tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
tmp |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK;
writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
return 0;
}