[Xen-devel] [PATCH v4 16/23] xen/arm: generate vpl011 node on device tree for domU

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Introduce vpl011 support to guests started from Xen: it provides a
simple way to print output from a guest, as most guests come with a
pl011 driver. It is also able to provide a working console with
interrupt support.

The UART exposed to the guest is a SBSA compatible UART and not a PL011.
SBSA UART is a subset of PL011 r1p5. A full PL011 implementation in Xen
would just be too difficult, so guests may require some drivers changes.

Enable vpl011 conditionally if the user requested it.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
---
Changes in v4:
- move rename set_interrupt_ppi and making set_interrupt_ppi generic to
  a separate patch
- properly name the vpl011 device node name
- code style
- use #define for addrcells and sizecells

Changes in v3:
- use bool
- retain BUG_ON(irq < 16)
- add vpl011 bool to kinfo
- return error of vpl011 is required but CONFIG_SBSA_VUART_CONSOLE is
  missing

Changes in v2:
- code style fixes
- make set_interrupt_ppi generic
- rename set_interrupt_ppi to set_interrupt
- only make the vpl011 node if the option was enabled
---
 xen/arch/arm/domain_build.c | 61 +++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/kernel.h       |  3 +++
 2 files changed, 64 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 760ebf8..049ab84 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1605,6 +1605,54 @@ static int __init make_timer_domU_node(const struct 
domain *d, void *fdt)
     return res;
 }
 
+#ifdef CONFIG_SBSA_VUART_CONSOLE
+static int __init make_vpl011_uart_node(const struct domain *d, void *fdt)
+{
+    int res;
+    gic_interrupt_t intr;
+    __be32 reg[GUEST_ROOT_ADDRESS_CELLS + GUEST_ROOT_SIZE_CELLS];
+    __be32 *cells;
+
+    res = fdt_begin_node(fdt, "sbsa-uart@"__stringify(GUEST_PL011_BASE));
+    if ( res )
+        return res;
+
+    res = fdt_property_string(fdt, "compatible", "arm,sbsa-uart");
+    if ( res )
+        return res;
+
+    cells = &reg[0];
+    dt_child_set_range(&cells, GUEST_ROOT_ADDRESS_CELLS,
+                       GUEST_ROOT_SIZE_CELLS, GUEST_PL011_BASE,
+                       GUEST_PL011_SIZE);
+    if ( res )
+        return res;
+    res = fdt_property(fdt, "reg", reg, sizeof(reg));
+    if ( res )
+        return res;
+
+    set_interrupt(intr, GUEST_VPL011_SPI, 0xf, DT_IRQ_TYPE_LEVEL_HIGH);
+
+    res = fdt_property(fdt, "interrupts", intr, sizeof (intr));
+    if ( res )
+        return res;
+
+    res = fdt_property_cell(fdt, "interrupt-parent",
+                            GUEST_PHANDLE_GIC);
+    if ( res )
+        return res;
+
+    /* Use a default baud rate of 115200. */
+    fdt_property_u32(fdt, "current-speed", 115200);
+
+    res = fdt_end_node(fdt);
+    if ( res )
+        return res;
+
+    return 0;
+}
+#endif
+
 /*
  * The max size for DT is 2MB. However, the generated DT is small, 4KB
  * are enough for now, but we might have to increase it in the future.
@@ -1666,6 +1714,16 @@ static int __init prepare_dtb_domU(struct domain *d, 
struct kernel_info *kinfo)
     if ( ret )
         goto err;
 
+    if ( kinfo->vpl011 )
+    {
+        ret = -EINVAL;
+#ifdef CONFIG_SBSA_VUART_CONSOLE
+        ret = make_vpl011_uart_node(d, kinfo->fdt);
+#endif
+        if ( ret )
+            goto err;
+    }
+
     ret = fdt_end_node(kinfo->fdt);
     if ( ret < 0 )
         goto err;
@@ -2523,6 +2581,7 @@ static int __init construct_domU(struct domain *d,
     struct kernel_info kinfo = {};
     int rc;
     u64 mem;
+    u32 len;
 
     rc = dt_property_read_u64(node, "memory", &mem);
     if ( !rc )
@@ -2534,6 +2593,8 @@ static int __init construct_domU(struct domain *d,
 
     printk("*** LOADING DOMU cpus=%u memory=%luKB ***\n", d->max_vcpus, mem);
 
+    kinfo.vpl011 = dt_get_property(node, "vpl011", &len) != NULL;
+
     d->vcpu = xzalloc_array(struct vcpu *, d->max_vcpus);
     if ( !d->vcpu )
         return -ENOMEM;;
diff --git a/xen/arch/arm/kernel.h b/xen/arch/arm/kernel.h
index 4320f72..33f3e72 100644
--- a/xen/arch/arm/kernel.h
+++ b/xen/arch/arm/kernel.h
@@ -33,6 +33,9 @@ struct kernel_info {
     paddr_t dtb_paddr;
     paddr_t initrd_paddr;
 
+    /* Enable pl011 emulation */
+    bool vpl011;
+
     /* loader to use for this kernel */
     void (*load)(struct kernel_info *info);
     /* loader specific state */
-- 
1.9.1


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