[PATCH v2] PCI: Cadence: Add quirk for Gen2 controller to do autonomous speed change.

From: Nadeem Athani
Date: Wed Sep 23 2020 - 14:34:52 EST


Cadence controller will not initiate autonomous speed change if
strapped as Gen2. The Retrain bit is set as a quirk to trigger
this speed change.

Signed-off-by: Nadeem Athani <nadeem@xxxxxxxxxxx>
---
drivers/pci/controller/cadence/pcie-cadence-host.c | 14 ++++++++++++++
drivers/pci/controller/cadence/pcie-cadence.h | 15 +++++++++++++++
2 files changed, 29 insertions(+)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 4550e0d469ca..a2317614268d 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -83,6 +83,9 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
struct cdns_pcie *pcie = &rc->pcie;
u32 value, ctrl;
u32 id;
+ u32 link_cap = CDNS_PCIE_LINK_CAP_OFFSET;
+ u8 sls;
+ u16 lnk_ctl;

/*
* Set the root complex BAR configuration register:
@@ -111,6 +114,17 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
if (rc->device_id != 0xffff)
cdns_pcie_rp_writew(pcie, PCI_DEVICE_ID, rc->device_id);

+ /* Quirk to enable autonomous speed change for GEN2 controller */
+ /* Reading Supported Link Speed value */
+ sls = PCI_EXP_LNKCAP_SLS &
+ cdns_pcie_rp_readb(pcie, link_cap + PCI_EXP_LNKCAP);
+ if (sls == PCI_EXP_LNKCAP_SLS_5_0GB) {
+ /* Since this a Gen2 controller, set Retrain Link(RL) bit */
+ lnk_ctl = cdns_pcie_rp_readw(pcie, link_cap + PCI_EXP_LNKCTL);
+ lnk_ctl |= PCI_EXP_LNKCTL_RL;
+ cdns_pcie_rp_writew(pcie, link_cap + PCI_EXP_LNKCTL, lnk_ctl);
+ }
+
cdns_pcie_rp_writeb(pcie, PCI_CLASS_REVISION, 0);
cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index feed1e3038f4..fe560480c573 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -120,6 +120,7 @@
*/
#define CDNS_PCIE_RP_BASE 0x00200000

+#define CDNS_PCIE_LINK_CAP_OFFSET 0xC0

/*
* Address Translation Registers
@@ -413,6 +414,20 @@ static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie,
cdns_pcie_write_sz(addr, 0x2, value);
}

+static inline u8 cdns_pcie_rp_readb(struct cdns_pcie *pcie, u32 reg)
+{
+ void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
+
+ return cdns_pcie_read_sz(addr, 0x1);
+}
+
+static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg)
+{
+ void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
+
+ return cdns_pcie_read_sz(addr, 0x2);
+}
+
/* Endpoint Function register access */
static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
u32 reg, u8 value)
--
2.15.0