xen/arm: platform: Add Raspberry Pi platform

The aux peripherals (uart1, spi1, and spi2) share an IRQ and a page of
memory. For debugging, it is helpful to use the aux UART in Xen. In
this case, Xen would try to assign spi1 and spi2 to dom0, but this
results in an error since the shared IRQ was already assigned to Xen.
Blacklist aux devices other than the UART to prevent mapping the shared
IRQ and memory range to dom0.

Blacklisting spi1 and spi2 unfortunately makes those peripherals
unavailable for use in the system. Future work could include forwarding
the IRQ for spi1 and spi2, and trap and mediate access to the memory
range for spi1 and spi2.

Signed-off-by: Stewart Hildebrand <stewart.hildebrand@dornerworks.com>
Acked-by: Julien Grall <julien.grall@arm.com>

xen/arch/arm/platforms/Makefile

@@ -8,5 +8,6 @@ obj-$(CONFIG_ALL64_PLAT) += seattle.o
 obj-$(CONFIG_ALL_PLAT)   += sunxi.o
 obj-$(CONFIG_ALL64_PLAT) += thunderx.o
 obj-$(CONFIG_ALL64_PLAT) += xgene-storm.o
+obj-$(CONFIG_ALL64_PLAT) += brcm-raspberry-pi.o
 obj-$(CONFIG_MPSOC_PLATFORM)  += xilinx-zynqmp.o
 obj-$(CONFIG_MPSOC_PLATFORM)  += xilinx-zynqmp-eemi.o

xen/arch/arm/platforms/brcm-raspberry-pi.c

@@ -0,0 +1,55 @@
+/*
+ * xen/arch/arm/platforms/brcm-raspberry-pi.c
+ *
+ * Raspberry Pi 4 Platform specific settings.
+ *
+ * Stewart Hildebrand <stewart.hildebrand@dornerworks.com>
+ * Copyright (c) 2019 DornerWorks, Ltd
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 <asm/platform.h>
+
+static const char *const brcm_bcm2838_dt_compat[] __initconst =
+{
+    "brcm,bcm2838",
+    NULL
+};
+
+static const struct dt_device_match brcm_bcm2838_blacklist_dev[] __initconst =
+{
+    /*
+     * The aux SPIs share an IRQ and a page with the aux UART.
+     * If the same page gets mapped to dom0 and Xen, there is risk of
+     * dom0 writing to the UART that Xen controls.
+     */
+    DT_MATCH_COMPATIBLE("brcm,bcm2835-aux-spi"),
+    /*
+     * The aux peripheral also shares a page with the aux UART.
+     */
+    DT_MATCH_COMPATIBLE("brcm,bcm2835-aux"),
+    { /* sentinel */ },
+};
+
+PLATFORM_START(brcm_bcm2838, "Raspberry Pi 4")
+    .compatible     = brcm_bcm2838_dt_compat,
+    .blacklist_dev  = brcm_bcm2838_blacklist_dev,
+PLATFORM_END
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */