[Stratos-dev] Re: [PATCH V5 6/6] libxl: Allocate MMIO params for GPIO device and update DT

(+ Bertrand)

Hi Viresh,

On 22/08/2022 10:15, Viresh Kumar wrote:

This patch allocates Virtio MMIO params (IRQ and memory region) and pass them to the backend, also update Guest device-tree based on Virtio GPIO DT bindings [1].

[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio-virti...

Reviewed-by: Oleksandr Tyshchenko oleksandr_tyshchenko@epam.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org

---

tools/libs/light/libxl_arm.c | 51 ++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+)

diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c index 4c1012e56893..86c1e560900f 100644 --- a/tools/libs/light/libxl_arm.c +++ b/tools/libs/light/libxl_arm.c @@ -121,6 +121,15 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc, return rc; }

• for (i = 0; i < d_config->num_gpios; i++) {

•    libxl_device_gpio *gpio = &d_config->gpios[i];
  

• int rc = alloc_virtio_mmio_params(gc, &gpio->base, &gpio->irq,

•                                  &virtio_mmio_base, &virtio_mmio_irq);
  

• if (rc)

•    return rc;
  

• }

• /*
   * Every virtio-mmio device uses one emulated SPI. If Virtio devices are
   * present, make sure that we allocate enough SPIs for them.
  

@@ -984,6 +993,38 @@ static int make_virtio_mmio_node_i2c(libxl__gc *gc, void *fdt, uint64_t base, return fdt_end_node(fdt); } +static int make_virtio_mmio_node_gpio(libxl__gc *gc, void *fdt, uint64_t base,

•                                  uint32_t irq, uint32_t backend_domid)
  

+{

• int res;
• res = make_virtio_mmio_node_common(gc, fdt, base, irq, backend_domid);
• if (res) return res;
• res = fdt_begin_node(fdt, "gpio");
• if (res) return res;
• res = fdt_property_compat(gc, fdt, 1, "virtio,device29");

It is a very descriptive compatible :). And yes I realize this is the compatible chosen by upstream.

• if (res) return res;
• res = fdt_property(fdt, "gpio-controller", NULL, 0);
• if (res) return res;
• res = fdt_property_cell(fdt, "#gpio-cells", 2);
• if (res) return res;
• res = fdt_property(fdt, "interrupt-controller", NULL, 0);
• if (res) return res;
• res = fdt_property_cell(fdt, "#interrupt-cells", 2);
• if (res) return res;
• res = fdt_end_node(fdt);
• if (res) return res;
• return fdt_end_node(fdt);

+}

• static const struct arch_info *get_arch_info(libxl__gc *gc, const struct xc_dom_image *dom) {

@@ -1317,6 +1358,16 @@ static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_config *d_config, i2c->backend_domid) ); }

•    for (i = 0; i < d_config->num_gpios; i++) {
  

•        libxl_device_gpio *gpio = &d_config->gpios[i];
  

•        if (gpio->backend_domid != LIBXL_TOOLSTACK_DOMID)
  

•            iommu_needed = true;
  

•        FDT( make_virtio_mmio_node_gpio(gc, fdt, gpio->base, gpio->irq,
  

•                                        gpio->backend_domid) );
  

So this is exposing a GPIO interrupt controller but IIUC we will also need to describe the devices in the device-tree. Can you outline how you would expect it to work?

To put some context, this is related to what I wrote in patch #1. How much code will be necessary in libxl to add new device?

I am not the maintainer of this code, but I would expect some example how this can be used once this merged. This would help us to understand whether the interface is correct.

Cheers,