skylake: Support common LPSS I2C driver

Support the common Intel LPSS I2C driver for the 6 I2C bus controllers
that are present on the Skylake-LP PCH with a 120 mHz clock.  The
required lpss_i2c_base_address() method is implemented separately for
verstage/romstage and ramstage environments.

This provides methods to convert to and from "struct device" and the
I2C controller bus number for that device.  These are used to provide
support for the "I2C Bus Operations" that are present in the coreboot
devicetree.

To support the I2C controller before ramstage an early init function
is provided to do minimal initializaiton of the PCI device and assign
a temporary base address for use before memory.  The final base
address is assigned during device enumeration and used during ramstage.

Because it is usually not necessary to enable I2C controllers before
ramstage a config register for the devicetree is provided to perform
early initialization of this controller.  In addition the bus speed
can be set in the devicetree and that speed will be applied when the
device is initialized.  If not provided the default speed is set to
I2C_SPEED_FAST.

This was tested with the google/chell mainboard by reading and writing
from the trackpad and codec devices during both verstage and ramstage.

Change-Id: Ia0270adfaf2843a3be4e00c732c85401a3401ef5
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/15105
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/intel/skylake/Kconfig

@@ -37,6 +37,7 @@ config CPU_SPECIFIC_OPTIONS
 	select RELOCATABLE_RAMSTAGE
 	select SOC_INTEL_COMMON
 	select SOC_INTEL_COMMON_ACPI_WAKE_SOURCE
+	select SOC_INTEL_COMMON_LPSS_I2C
 	select SOC_INTEL_COMMON_RESET
 	select SMM_TSEG
 	select SMP
@@ -72,6 +73,10 @@ config CPU_ADDR_BITS
 	int
 	default 36
 
+config SOC_INTEL_COMMON_LPSS_I2C_CLOCK_MHZ
+	int
+	default 120
+
 config DCACHE_RAM_BASE
 	hex "Base address of cache-as-RAM"
 	default 0xfef00000

src/soc/intel/skylake/chip.h

@@ -20,6 +20,7 @@
 #define _SOC_CHIP_H_
 
 #include <arch/acpi_device.h>
+#include <device/i2c.h>
 #include <stdint.h>
 #include <soc/gpio_defs.h>
 #include <soc/gpe.h>
@@ -39,6 +40,10 @@ enum skylake_i2c_voltage {
 struct skylake_i2c_config {
 	/* Bus voltage level, default is 3.3V */
 	enum skylake_i2c_voltage voltage;
+	/* Bus speed in Hz, default is I2C_SPEED_FAST (400 KHz) */
+	enum i2c_speed speed;
+	/* Bus should be enabled prior to ramstage with temporary base */
+	int early_init;
 };
 
 struct soc_intel_skylake_config {

src/soc/intel/skylake/i2c.c

@@ -14,16 +14,66 @@
  */
 
 #include <device/device.h>
+#include <device/i2c.h>
 #include <device/pci.h>
 #include <device/pci_ids.h>
+#include <soc/intel/common/lpss_i2c.h>
 #include <soc/ramstage.h>
 
+uintptr_t lpss_i2c_base_address(unsigned bus)
+{
+	unsigned devfn;
+	struct device *dev;
+	struct resource *res;
+
+	/* bus -> devfn */
+	devfn = i2c_bus_to_devfn(bus);
+	if (devfn >= 0) {
+		/* devfn -> dev */
+		dev = dev_find_slot(0, devfn);
+		if (dev) {
+			/* dev -> bar0 */
+			res = find_resource(dev, PCI_BASE_ADDRESS_0);
+			if (res)
+				return res->base;
+		}
+	}
+
+	return (uintptr_t)NULL;
+}
+
+static int i2c_dev_to_bus(struct device *dev)
+{
+	return i2c_devfn_to_bus(dev->path.pci.devfn);
+}
+
+/*
+ * The device should already be enabled and out of reset,
+ * either from early init in coreboot or SiliconInit in FSP.
+ */
+static void i2c_dev_init(struct device *dev)
+{
+	struct soc_intel_skylake_config *config = dev->chip_info;
+	int bus = i2c_dev_to_bus(dev);
+
+	if (!config || bus < 0)
+		return;
+
+	lpss_i2c_init(bus, config->i2c[bus].speed ? : I2C_SPEED_FAST);
+}
+
+static struct i2c_bus_operations i2c_bus_ops = {
+	.dev_to_bus		= &i2c_dev_to_bus,
+};
+
 static struct device_operations i2c_dev_ops = {
 	.read_resources		= &pci_dev_read_resources,
 	.set_resources		= &pci_dev_set_resources,
 	.enable_resources	= &pci_dev_enable_resources,
 	.scan_bus		= &scan_smbus,
 	.ops_pci		= &soc_pci_ops,
+	.ops_i2c_bus		= &i2c_bus_ops,
+	.init			= &i2c_dev_init,
 };
 
 static const unsigned short pci_device_ids[] = {

src/soc/intel/skylake/include/soc/iomap.h

@@ -29,6 +29,9 @@
 #define UART_DEBUG_BASE_ADDRESS	0xfe034000
 #define UART_DEBUG_BASE_SIZE	0x1000
 
+#define EARLY_I2C_BASE_ADDRESS	0xfe040000
+#define EARLY_I2C_BASE(x)	(EARLY_I2C_BASE_ADDRESS + (0x1000 * (x)))
+
 #define MCH_BASE_ADDRESS	0xfed10000
 #define MCH_BASE_SIZE		0x8000
 

src/soc/intel/skylake/include/soc/pci_devs.h

@@ -17,6 +17,7 @@
 #ifndef _SOC_PCI_DEVS_H_
 #define _SOC_PCI_DEVS_H_
 
+#include <device/pci_def.h>
 #include <rules.h>
 
 #define _SA_DEVFN(slot)		PCI_DEVFN(SA_DEV_SLOT_ ## slot, 0)
@@ -147,4 +148,32 @@
 #define  PCH_DEV_SPI		_PCH_DEV(LPC, 5)
 #define  PCH_DEV_GBE		_PCH_DEV(LPC, 6)
 
+/* Convert I2C bus number to PCI device and function */
+static inline int i2c_bus_to_devfn(unsigned bus)
+{
+	switch (bus) {
+	case 0: return PCH_DEVFN_I2C0;
+	case 1: return PCH_DEVFN_I2C1;
+	case 2: return PCH_DEVFN_I2C2;
+	case 3: return PCH_DEVFN_I2C3;
+	case 4: return PCH_DEVFN_I2C4;
+	case 5: return PCH_DEVFN_I2C5;
+	}
+	return -1;
+}
+
+/* Convert PCI device and function to I2C bus number */
+static inline int i2c_devfn_to_bus(unsigned devfn)
+{
+	switch (devfn) {
+	case PCH_DEVFN_I2C0: return 0;
+	case PCH_DEVFN_I2C1: return 1;
+	case PCH_DEVFN_I2C2: return 2;
+	case PCH_DEVFN_I2C3: return 3;
+	case PCH_DEVFN_I2C4: return 4;
+	case PCH_DEVFN_I2C5: return 5;
+	}
+	return -1;
+}
+
 #endif

src/soc/intel/skylake/include/soc/romstage.h

@@ -19,6 +19,7 @@
 
 #include <fsp/romstage.h>
 
+void i2c_early_init(void);
 void systemagent_early_init(void);
 void pch_early_init(void);
 void pch_uart_init(void);

src/soc/intel/skylake/romstage/Makefile.inc

@@ -1,4 +1,5 @@
 verstage-y += cpu.c
+verstage-y += i2c.c
 verstage-y += pch.c
 verstage-y += power_state.c
 verstage-y += report_platform.c
@@ -9,6 +10,7 @@ verstage-y += systemagent.c
 verstage-y += uart.c
 
 romstage-y += cpu.c
+romstage-y += i2c.c
 romstage-y += pch.c
 romstage-y += power_state.c
 romstage-y += report_platform.c

src/soc/intel/skylake/romstage/i2c.c

@@ -0,0 +1,97 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <arch/io.h>
+#include <commonlib/helpers.h>
+#include <device/device.h>
+#include <device/i2c.h>
+#include <device/pci_def.h>
+#include <soc/intel/common/lpss_i2c.h>
+#include <soc/iomap.h>
+#include <soc/pci_devs.h>
+#include <soc/romstage.h>
+#include <soc/serialio.h>
+#include "chip.h"
+
+uintptr_t lpss_i2c_base_address(unsigned bus)
+{
+	unsigned devfn;
+	pci_devfn_t dev;
+
+	/* Find device+function for this controller */
+	devfn = i2c_bus_to_devfn(bus);
+	if (devfn < 0)
+		return 0;
+
+	/* Form a PCI address for this device */
+	dev = PCI_DEV(0, PCI_SLOT(devfn), PCI_FUNC(devfn));
+
+	/* Read the first base address for this device */
+	return ALIGN_DOWN(pci_read_config32(dev, PCI_BASE_ADDRESS_0), 16);
+}
+
+static void i2c_early_init_bus(unsigned bus)
+{
+	ROMSTAGE_CONST struct soc_intel_skylake_config *config;
+	ROMSTAGE_CONST struct device *tree_dev;
+	pci_devfn_t dev;
+	unsigned devfn;
+	uintptr_t base;
+	uint32_t value;
+	void *reg;
+
+	/* Find the PCI device for this bus controller */
+	devfn = i2c_bus_to_devfn(bus);
+	if (devfn < 0)
+		return;
+
+	/* Look up the controller device in the devicetree */
+	dev = PCI_DEV(0, PCI_SLOT(devfn), PCI_FUNC(devfn));
+	tree_dev = dev_find_slot(0, devfn);
+	if (!tree_dev || !tree_dev->enabled)
+		return;
+
+	/* Skip if not enabled for early init */
+	config = tree_dev->chip_info;
+	if (!config)
+		return;
+	if (!config->i2c[bus].early_init)
+		return;
+
+	/* Prepare early base address for access before memory */
+	base = EARLY_I2C_BASE(bus);
+	pci_write_config32(dev, PCI_BASE_ADDRESS_0, base);
+	pci_write_config32(dev, PCI_COMMAND,
+			   PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER);
+
+	/* Take device out of reset */
+	reg = (void *)(base + SIO_REG_PPR_RESETS);
+	value = read32(reg);
+	value |= SIO_REG_PPR_RESETS_FUNC | SIO_REG_PPR_RESETS_APB |
+		SIO_REG_PPR_RESETS_IDMA;
+	write32(reg, value);
+
+	/* Initialize the controller */
+	lpss_i2c_init(bus, config->i2c[bus].speed ? : I2C_SPEED_FAST);
+}
+
+void i2c_early_init(void)
+{
+	int bus;
+
+	/* Initialize I2C controllers that are enabled in devicetree */
+	for (bus = 0; bus < SKYLAKE_I2C_DEV_MAX; bus++)
+		i2c_early_init_bus(bus);
+}

src/soc/intel/skylake/romstage/romstage.c

@@ -64,6 +64,7 @@ void car_soc_post_console_init(void)
 	report_platform_info();
 	set_max_freq();
 	pch_early_init();
+	i2c_early_init();
 }
 
 int get_sw_write_protect_state(void)