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From faca7230ba711f7f966cd51bf46f83c5848a8623 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Thu, 11 Jun 2020 09:57:03 +0100
Subject: [PATCH] PCI: brcmstb: Add DT property to control L1SS
The BRCM PCIe block has controls to enable control of the CLKREQ#
signal by the L1SS, and to gate the refclk with the CLKREQ# input.
These controls are mutually exclusive - the upstream code sets the
latter, but some use cases require the former.
Add a Device Tree property - brcm,enable-l1ss - to switch to the
L1SS configuration.
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/pci/controller/pcie-brcmstb.c | 30 ++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -102,8 +102,9 @@
PCIE_MISC_CPU_2_PCIE_MEM_WIN0_LIMIT_HI + ((win) * 8)
#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_SERDES_IDDQ_MASK 0x08000000
+#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK BIT(1)
+#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_L1SS_ENABLE_MASK BIT(21)
+#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK BIT(27)
#define PCIE_MSI_INTR2_STATUS 0x4500
#define PCIE_MSI_INTR2_CLR 0x4508
@@ -170,6 +171,7 @@ struct brcm_pcie {
struct pci_bus *root_bus;
struct device_node *np;
bool ssc;
+ bool l1ss;
int gen;
u64 msi_target_addr;
struct brcm_msi *msi;
@@ -834,12 +836,25 @@ static int brcm_pcie_setup(struct brcm_p
PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1_ENDIAN_MODE_BAR2_MASK);
writel(tmp, base + PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1);
- /*
- * 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;
+ if (pcie->l1ss) {
+ /*
+ * Enable CLKREQ# signalling include L1 Substate control of
+ * the CLKREQ# signal and the external reference clock buffer.
+ * meet requirement for Endpoints that require CLKREQ#
+ * assertion to clock active within 400ns.
+ */
+ tmp &= ~PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK;
+ tmp |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_L1SS_ENABLE_MASK;
+ } else {
+ /*
+ * Refclk from RC should be gated with CLKREQ# input when
+ * ASPM L0s,L1 is enabled => setting the CLKREQ_DEBUG_ENABLE
+ * field to 1.
+ */
+ tmp &= ~PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_L1SS_ENABLE_MASK;
+ tmp |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK;
+ }
writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
return 0;
@@ -944,6 +959,7 @@ static int brcm_pcie_probe(struct platfo
pcie->gen = (ret < 0) ? 0 : ret;
pcie->ssc = of_property_read_bool(np, "brcm,enable-ssc");
+ pcie->l1ss = of_property_read_bool(np, "brcm,enable-l1ss");
ret = pci_parse_request_of_pci_ranges(pcie->dev, &bridge->windows,
&bridge->dma_ranges, NULL);
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