drivers/generic/bayhub: Add driver for BayHub BH720

Add a driver which puts the device into power-saving mode.

BUG=b:73726008
BRANCH=none
TEST=boot and see this message:
BayHub BH720: Power-saving enabled 110103
From linux:
$ iotools pci_read32 2 0 0 0x90
0x00110103

Change-Id: Idbfb114f3782c9386ce9b487c3abdb0afbc4a0d9
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://review.coreboot.org/25966
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/drivers/generic/bayhub/Kconfig

@@ -0,0 +1,2 @@
+config DRIVERS_GENERIC_BH720
+	bool

src/drivers/generic/bayhub/Makefile.inc

@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_GENERIC_BH720) += bh720.c

src/drivers/generic/bayhub/bh720.c

@@ -0,0 +1,93 @@
+/*
+ * Driver for BayHub Technology BH720 PCI to eMMC 5.0 HS200 bridge
+ *
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2018 Google LLC.
+ *
+ * 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 <console/console.h>
+#include <device/device.h>
+#include <device/path.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include "chip.h"
+
+enum {
+	BH720_PROTECT			= 0xd0,
+	BH720_PROTECT_OFF		= 0,
+	BH720_PROTECT_ON		= 1,
+
+	BH720_RTD3_L1			= 0x3e0,
+	BH720_RTD3_L1_DISABLE_L1	= BIT(28),
+
+	BH720_LINK_CTRL			= 0x90,
+	BH720_LINK_CTRL_L0_ENABLE	= BIT(0),
+	BH720_LINK_CTRL_L1_ENABLE	= BIT(1),
+	BH720_LINK_CTRL_CLKREQ		= BIT(8),
+};
+
+static void bh720_init(struct device *dev)
+{
+	struct drivers_generic_bayhub_config *config = dev->chip_info;
+
+	pci_dev_init(dev);
+
+	if (config && config->power_saving) {
+		/*
+		 * This procedure for enabling power-saving mode is from the
+		 * BayHub BIOS Implementation Guideline document.
+		 */
+		pci_write_config32(dev, BH720_PROTECT, BH720_PROTECT_OFF);
+		pci_or_config32(dev, BH720_RTD3_L1, BH720_RTD3_L1_DISABLE_L1);
+		pci_or_config32(dev, BH720_LINK_CTRL,
+				BH720_LINK_CTRL_L0_ENABLE |
+				BH720_LINK_CTRL_L1_ENABLE);
+		pci_or_config32(dev, BH720_LINK_CTRL, BH720_LINK_CTRL_CLKREQ);
+		pci_write_config32(dev, BH720_PROTECT, BH720_PROTECT_ON);
+		printk(BIOS_INFO, "BayHub BH720: Power-saving enabled (link_ctrl=%#x)\n",
+		       pci_read_config32(dev, BH720_LINK_CTRL));
+	}
+}
+
+static struct pci_operations pci_ops = {
+	.set_subsystem = pci_dev_set_subsystem,
+};
+
+static struct device_operations bh720_ops = {
+	.read_resources		= pci_dev_read_resources,
+	.set_resources		= pci_dev_set_resources,
+	.enable_resources	= pci_dev_enable_resources,
+	.ops_pci		= &pci_ops,
+	.init			= bh720_init,
+};
+
+static const unsigned short pci_device_ids[] = {
+	PCI_DEVICE_ID_O2_BH720,
+	0
+};
+
+static const struct pci_driver bayhub_bh720 __pci_driver = {
+	.ops		= &bh720_ops,
+	.vendor		= PCI_VENDOR_ID_O2,
+	.devices	= pci_device_ids,
+};
+
+static void bh720_enable(struct device *dev)
+{
+	dev->ops = &bh720_ops;
+}
+
+struct chip_operations bayhub_bh720_ops = {
+	CHIP_NAME("BayHub Technology BH720 PCI to eMMC 5.0 HS200 bridge")
+	.enable_dev = bh720_enable,
+};

src/drivers/generic/bayhub/chip.h

@@ -0,0 +1,24 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2018 Google LLC.
+ *
+ * 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/acpi_device.h>
+
+/*
+ * Bayhub BG720 PCI to eMMC bridge
+ */
+struct drivers_generic_bayhub_config {
+	/* 1 to enable power-saving mode, 0 to disable */
+	int power_saving;
+};

src/include/device/pci_ids.h

@@ -1688,6 +1688,7 @@
 #define PCI_DEVICE_ID_O2_6730		0x673a
 #define PCI_DEVICE_ID_O2_6832		0x6832
 #define PCI_DEVICE_ID_O2_6836		0x6836
+#define PCI_DEVICE_ID_O2_BH720		0x8620
 
 #define PCI_VENDOR_ID_3DFX		0x121a
 #define PCI_DEVICE_ID_3DFX_VOODOO	0x0001