1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
From ebabd0b257fd8863e8038e9fd5b3b8428b06cfe2 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 | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -120,6 +120,7 @@
#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_BMIPS_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK 0x00800000
+#define PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_L1SS_ENABLE_MASK 0x00200000
#define PCIE_INTR2_CPU_BASE 0x4300
@@ -249,6 +250,7 @@ struct brcm_pcie {
struct clk *clk;
struct device_node *np;
bool ssc;
+ bool l1ss;
int gen;
u64 msi_target_addr;
struct brcm_msi *msi;
@@ -1062,12 +1064,25 @@ static int brcm_pcie_start_link(struct b
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;
+ 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;
@@ -1523,6 +1538,7 @@ 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 = clk_prepare_enable(pcie->clk);
if (ret) {
|