soc/intel/common: Enable support to write protect SPI flash range

Write-protect SPI flash range provided by caller by using a free Flash
Protected Range (FPR) register. This expects SoC to define a callback
for providing information about the first FPR register address and
maximum number of FPRs supported.

BUG=chrome-os-partner:58896

Change-Id: I4e34ede8784e5587a5e08ffa10e20d2d14e20add
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17115
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/intel/common/Kconfig

@@ -9,6 +9,10 @@ config CACHE_MRC_SETTINGS
 	bool "Save cached MRC settings"
 	default n
 
+config SOC_INTEL_COMMON_SPI_PROTECT
+	bool
+	default n
+
 if CACHE_MRC_SETTINGS
 
 config MRC_SETTINGS_CACHE_BASE

src/soc/intel/common/Makefile.inc

@@ -19,6 +19,7 @@ postcar-y += util.c
 ramstage-y += hda_verb.c
 ramstage-$(CONFIG_CACHE_MRC_SETTINGS) += mrc_cache.c
 ramstage-$(CONFIG_CACHE_MRC_SETTINGS) += nvm.c
+ramstage-$(CONFIG_SOC_INTEL_COMMON_SPI_PROTECT) += spi.c
 ramstage-$(CONFIG_SOC_INTEL_COMMON_LPSS_I2C) += lpss_i2c.c
 ramstage-$(CONFIG_SOC_INTEL_COMMON_RESET) += reset.c
 ramstage-y += util.c

src/soc/intel/common/nvm.c

@@ -20,9 +20,9 @@
 #include <string.h>
 #include <spi-generic.h>
 #include <spi_flash.h>
-#include <soc/spi.h>
 #include <vendorcode/google/chromeos/chromeos.h>
 #include "nvm.h"
+#include "spi.h"
 
 /* This module assumes the flash is memory mapped just below 4GiB in the
  * address space for reading. Also this module assumes an area it erased

src/soc/intel/common/spi.c

@@ -0,0 +1,66 @@
+/*
+ * 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 <console/console.h>
+#include "spi.h"
+
+/*
+ * Protect range of SPI flash defined by [start, start+size-1] using Flash
+ * Protected Range (FPR) register if available.
+ */
+int spi_flash_protect(u32 start, u32 size)
+{
+	struct fpr_info fpr_info;
+	u32 end = start + size - 1;
+	u32 reg;
+	int fpr;
+	uintptr_t fpr_base;
+
+	if (spi_get_fpr_info(&fpr_info) == -1) {
+		printk(BIOS_ERR, "ERROR: FPR Info not found!\n");
+		return -1;
+	}
+
+	fpr_base = fpr_info.base;
+
+	/* Find first empty FPR */
+	for (fpr = 0; fpr < fpr_info.max; fpr++) {
+		reg = read32((void *)fpr_base);
+		if (reg == 0)
+			break;
+		fpr_base += sizeof(uint32_t);
+	}
+
+	if (fpr >= fpr_info.max) {
+		printk(BIOS_ERR, "ERROR: No SPI FPR free!\n");
+		return -1;
+	}
+
+	/* Set protected range base and limit */
+	reg = SPI_FPR(start, end) | SPI_FPR_WPE;
+
+	/* Set the FPR register and verify it is protected */
+	write32((void *)fpr_base, reg);
+	reg = read32((void *)fpr_base);
+	if (!(reg & SPI_FPR_WPE)) {
+		printk(BIOS_ERR, "ERROR: Unable to set SPI FPR %d\n", fpr);
+		return -1;
+	}
+
+	printk(BIOS_INFO, "%s: FPR %d is enabled for range 0x%08x-0x%08x\n",
+	       __func__, fpr, start, end);
+	return 0;
+}

src/soc/intel/common/spi.h

@@ -0,0 +1,45 @@
+/*
+ * 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.
+ */
+
+#define SPI_FPR_SHIFT		12
+#define SPI_FPR_MASK		0x7fff
+#define SPI_FPR_BASE_SHIFT	0
+#define SPI_FPR_LIMIT_SHIFT	16
+#define SPI_FPR_RPE		(1 << 15) /* Read Protect */
+#define SPI_FPR_WPE		(1 << 31) /* Write Protect */
+#define SPI_FPR(base, limit)	\
+	(((((limit) >> SPI_FPR_SHIFT) & SPI_FPR_MASK) << SPI_FPR_LIMIT_SHIFT) |\
+	 ((((base) >> SPI_FPR_SHIFT) & SPI_FPR_MASK) << SPI_FPR_BASE_SHIFT))
+
+struct fpr_info {
+	/* Offset of first FPR register */
+	uintptr_t base;
+	/* Maximum number of FPR registers */
+	uint8_t max;
+};
+
+/*
+ * SoC is expected to implement this function to provide address of first FPR
+ * register and max count of FPR registers.
+ *
+ * On success return 0 else -1.
+ */
+int spi_get_fpr_info(struct fpr_info *info);
+
+/*
+ * Protect range of SPI flash defined by [start, start+size-1] using Flash
+ * Protected Range (FPR) register if available.
+ */
+int spi_flash_protect(u32 start, u32 size);