soc/intel/skylake: Set FSP options for PEG port

FSP options list (for each PEG port):
  - PegXEnable,
  - PegXMaxLinkWidth,
  - PegXMaxLinkSpeed,
  - PegXPowerDownUnusedLanes,
  - PegXGen3EqPh2Enable,
  - PegXGen3EqPh3Method.

Add PegMaxLinkWidth to chip.h. This option overrides the number of
active lines from the devicetree.cb for each enabled PEG port (for
example for boards that use x4 instead of x16 lines in PEG0). If the
PegMaxLinkWidth is not defined, the port uses the maximum possible
number of lines.

To enable or disable the corresponding PEG root port you need to add
to the devicetree.cb:

  device pci 01.0 on  end # enable PEG0 root port
  device pci 01.1 off end # do not configure PEG1

If PEG port is not defined in the devicetree, it will be disabled in
FSP.

It has been tested on ASRock H110M-DVS motherboard (Skylake i5-6600
CPU).

Change-Id: I23708f7060edf08739adf61fe61a419329907563
Signed-off-by: Maxim Polyakov <max.senia.poliak@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32045
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

3 files changed, 87 insertions, 0 deletions

diff --git a/src/soc/intel/skylake/chip.h b/src/soc/intel/skylake/chip.h
index a9b8641626..57d51e76b2 100644
--- a/src/soc/intel/skylake/chip.h
+++ b/src/soc/intel/skylake/chip.h
@@ -35,6 +35,8 @@
 #include <soc/usb.h>
 #include <soc/vr_config.h>
 
+#define MAX_PEG_PORTS	3
+
 enum skylake_i2c_voltage {
 	I2C_VOLTAGE_3V3,
 	I2C_VOLTAGE_1V8
@@ -213,6 +215,28 @@ struct soc_intel_skylake_config {
 	 * respective PCIe root port.
 	 */
 
+	/* PEG Max Link Width */
+	enum {
+		Peg0_x16,
+		Peg0_x1,
+		Peg0_x2,
+		Peg0_x4,
+		Peg0_x8,
+	} Peg0MaxLinkWidth;
+
+	enum {
+		Peg1_x8,
+		Peg1_x1,
+		Peg1_x2,
+		Peg1_x4,
+	} Peg1MaxLinkWidth;
+
+	enum {
+		Peg2_x4,
+		Peg2_x1,
+		Peg2_x2,
+	} Peg2MaxLinkWidth;
+
 	/*
 	 * Enable/Disable Root Port
 	 * 0: Disable Root Port
diff --git a/src/soc/intel/skylake/include/soc/pci_devs.h b/src/soc/intel/skylake/include/soc/pci_devs.h
index f6957940e5..d59c80008b 100644
--- a/src/soc/intel/skylake/include/soc/pci_devs.h
+++ b/src/soc/intel/skylake/include/soc/pci_devs.h
@@ -37,6 +37,13 @@
 #define  SA_DEVFN_ROOT		_SA_DEVFN(ROOT)
 #define  SA_DEV_ROOT		_SA_DEV(ROOT)
 
+#define SA_DEV_SLOT_PEG		0x01
+#define  SA_DEVFN_PEG(func)	PCI_DEVFN(SA_DEV_SLOT_PEG, func)
+#define  SA_DEV_PEG(func)	dev_find_slot(0, SA_DEVFN_PEG(func))
+#define  SA_DEV_PEG0		SA_DEV_PEG(0)
+#define  SA_DEV_PEG1		SA_DEV_PEG(1)
+#define  SA_DEV_PEG2		SA_DEV_PEG(2)
+
 #define SA_DEV_SLOT_IGD		0x02
 #define  SA_DEVFN_IGD		_SA_DEVFN(IGD)
 #define  SA_DEV_IGD		_SA_DEV(IGD)
diff --git a/src/soc/intel/skylake/romstage/romstage_fsp20.c b/src/soc/intel/skylake/romstage/romstage_fsp20.c
index b65c9ff935..d9b2706a8b 100644
--- a/src/soc/intel/skylake/romstage/romstage_fsp20.c
+++ b/src/soc/intel/skylake/romstage/romstage_fsp20.c
@@ -202,6 +202,61 @@ static void cpu_flex_override(FSP_M_CONFIG *m_cfg)
 	m_cfg->CpuRatio = (flex_ratio.lo >> 8) & 0xff;
 }
 
+static void soc_peg_init_params(FSP_M_CONFIG *m_cfg,
+			FSP_M_TEST_CONFIG *m_t_cfg,
+			const struct soc_intel_skylake_config *config)
+{
+	const struct device *dev;
+	/*
+	 * To enable or disable the corresponding PEG root port you need to
+	 * add to the devicetree.cb:
+	 *
+	 *     device pci 01.0 on  end # enable PEG0 root port
+	 *     device pci 01.1 off end # do not configure PEG1
+	 *
+	 * If PEG port is not defined in the device tree, it will be disabled
+	 * in FSP
+	 */
+	dev = SA_DEV_PEG0; /* PEG 0:1:0 */
+	if (!dev || !dev->enabled)
+		m_cfg->Peg0Enable = 0;
+	else if (dev->enabled) {
+		m_cfg->Peg0Enable = dev->enabled;
+		m_cfg->Peg0MaxLinkWidth = config->Peg0MaxLinkWidth;
+		/* Use maximum possible link speed */
+		m_cfg->Peg0MaxLinkSpeed = 0;
+		/* Power down unused lanes based on the max possible width */
+		m_cfg->Peg0PowerDownUnusedLanes = 1;
+		/* Set [Auto] for options to enable equalization methods */
+		m_t_cfg->Peg0Gen3EqPh2Enable = 2;
+		m_t_cfg->Peg0Gen3EqPh3Method = 0;
+	}
+
+	dev = SA_DEV_PEG1; /* PEG 0:1:1 */
+	if (!dev || !dev->enabled)
+		m_cfg->Peg1Enable = 0;
+	else if (dev->enabled) {
+		m_cfg->Peg1Enable = dev->enabled;
+		m_cfg->Peg1MaxLinkWidth = config->Peg1MaxLinkWidth;
+		m_cfg->Peg1MaxLinkSpeed = 0;
+		m_cfg->Peg1PowerDownUnusedLanes = 1;
+		m_t_cfg->Peg1Gen3EqPh2Enable = 2;
+		m_t_cfg->Peg1Gen3EqPh3Method = 0;
+	}
+
+	dev = SA_DEV_PEG2; /* PEG 0:1:2 */
+	if (!dev || !dev->enabled)
+		m_cfg->Peg2Enable = 0;
+	else if (dev->enabled) {
+		m_cfg->Peg2Enable = dev->enabled;
+		m_cfg->Peg2MaxLinkWidth = config->Peg2MaxLinkWidth;
+		m_cfg->Peg2MaxLinkSpeed = 0;
+		m_cfg->Peg2PowerDownUnusedLanes = 1;
+		m_t_cfg->Peg2Gen3EqPh2Enable = 2;
+		m_t_cfg->Peg2Gen3EqPh3Method = 0;
+	}
+}
+
 static void soc_memory_init_params(FSP_M_CONFIG *m_cfg,
 			const struct soc_intel_skylake_config *config)
 {
@@ -276,6 +331,7 @@ void platform_fsp_memory_init_params_cb(FSPM_UPD *mupd, uint32_t version)
 	config = dev->chip_info;
 
 	soc_memory_init_params(m_cfg, config);
+	soc_peg_init_params(m_cfg, m_t_cfg, config);
 
 	/* Skip creating Management Engine MBP HOB */
 	m_t_cfg->SkipMbpHob = 0x01;