Re: [PATCH v2 4/5] apple-gmux: support MMIO gmux on T2 Macs

Hans de Goede
2023-02-16T13:16:15Z

Hi,

On 2/16/23 13:23, Orlando Chamberlain wrote:
> In some newer dual gpu MacBooks, gmux is controlled by the T2 security
> chip, and acessed with MMIO. Add support for these gmux controllers
>
> Interestingly, the ACPI table only allocates 8 bytes for GMUX, but we
> actually need 16, and as such we request 16 with request_mem_region.
>
> Reading and writing from ports:
> 16 bytes from 0xfe0b0200 are used. 0x0 to 0x4 are where data
> to read appears, and where data to write goes. Writing to 0xe
> sets the gmux port being accessed, and writing to 0xf sends commands.
>
> These commands are 0x40 & data_length for write, and data_length for
> read, where data_length is 1, 2 or 4. Once byte base+0xf is 0, the
> command is done.
>
> Issues:
> As with other retina models, we can't switch DDC lines so
> switching at runtime doesn't work if the inactive gpu driver
> already disabled eDP due to it not being connected when that
> driver loaded.
>
> Additionally, turning on the dgpu back on the MacBookPro16,1 does
> not work.
>
> Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
> ---
> v1->v2: Document some chips present, and clarify which chips aren't
> present on MMIO gmux laptops.
> drivers/platform/x86/apple-gmux.c | 142 +++++++++++++++++++++++++++---
> include/linux/apple-gmux.h | 40 ++++++---
> 2 files changed, 158 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
> index 12a93fc49c36..5bac6dcfada0 100644
> --- a/drivers/platform/x86/apple-gmux.c
> +++ b/drivers/platform/x86/apple-gmux.c
> @@ -28,15 +28,17 @@
> * DOC: Overview
> *
> * gmux is a microcontroller built into the MacBook Pro to support dual GPUs:
> - * A `Lattice XP2`_ on pre-retinas, a `Renesas R4F2113`_ on retinas.
> + * A `Lattice XP2`_ on pre-retinas, a `Renesas R4F2113`_ on pre-T2 retinas.
> + * The chip used on T2 Macs is not known.
> *
> * (The MacPro6,1 2013 also has a gmux, however it is unclear why since it has
> * dual GPUs but no built-in display.)
> *
> * gmux is connected to the LPC bus of the southbridge. Its I/O ports are
> * accessed differently depending on the microcontroller: Driver functions
> - * to access a pre-retina gmux are infixed ``_pio_``, those for a retina gmux
> - * are infixed ``_index_``.
> + * to access a pre-retina gmux are infixed ``_pio_``, those for a pre-T2
> + * retina gmux are infixed ``_index_``, and those on T2 Macs are infixed
> + * with ``_mmio_``.
> *
> * .. _Lattice XP2:
> * http://www.latticesemi.com/en/Products/FPGAandCPLD/LatticeXP2.aspx
> @@ -47,6 +49,7 @@
> struct apple_gmux_config;
>
> struct apple_gmux_data {
> + u8 *__iomem iomem_base;
> unsigned long iostart;
> unsigned long iolen;
> const struct apple_gmux_config *config;
> @@ -209,6 +212,79 @@ static void gmux_index_write32(struct apple_gmux_data *gmux_data, int port,
> mutex_unlock(&gmux_data->index_lock);
> }
>
> +static int gmux_mmio_wait(struct apple_gmux_data *gmux_data)
> +{
> + int i = 200;
> + u8 gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> +
> + while (i && gwr) {
> + gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> + udelay(100);
> + i--;
> + }
> +
> + return !!i;
> +}
> +
> +static u8 gmux_mmio_read8(struct apple_gmux_data *gmux_data, int port)
> +{
> + u8 val;
> +
> + mutex_lock(&gmux_data->index_lock);
> + gmux_mmio_wait(gmux_data);
> + iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
> + iowrite8(GMUX_MMIO_READ | sizeof(val),
> + gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> + gmux_mmio_wait(gmux_data);
> + val = ioread8(gmux_data->iomem_base);
> + mutex_unlock(&gmux_data->index_lock);
> +
> + return val;
> +}
> +
> +static void gmux_mmio_write8(struct apple_gmux_data *gmux_data, int port,
> + u8 val)
> +{
> + mutex_lock(&gmux_data->index_lock);
> + gmux_mmio_wait(gmux_data);
> + iowrite8(val, gmux_data->iomem_base);
> +
> + iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
> + iowrite8(GMUX_MMIO_WRITE | sizeof(val),
> + gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> +
> + gmux_mmio_wait(gmux_data);
> + mutex_unlock(&gmux_data->index_lock);
> +}
> +
> +static u32 gmux_mmio_read32(struct apple_gmux_data *gmux_data, int port)
> +{
> + u32 val;
> +
> + mutex_lock(&gmux_data->index_lock);
> + gmux_mmio_wait(gmux_data);
> + iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
> + iowrite8(GMUX_MMIO_READ | sizeof(val),
> + gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> + gmux_mmio_wait(gmux_data);
> + val = be32_to_cpu(ioread32(gmux_data->iomem_base));
> + mutex_unlock(&gmux_data->index_lock);
> +
> + return val;
> +}
> +
> +static void gmux_mmio_write32(struct apple_gmux_data *gmux_data, int port,
> + u32 val)
> +{
> + mutex_lock(&gmux_data->index_lock);
> + iowrite32(cpu_to_be32(val), gmux_data->iomem_base);
> + iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
> + iowrite8(GMUX_MMIO_WRITE | sizeof(val),
> + gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
> + gmux_mmio_wait(gmux_data);
> + mutex_unlock(&gmux_data->index_lock);
> +}
> +
> static u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
> {
> return gmux_data->config->read8(gmux_data, port);
> @@ -237,8 +313,8 @@ static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
> * the GPU. On dual GPU MacBook Pros by contrast, either GPU may be suspended
> * to conserve energy. Hence the PWM signal needs to be generated by a separate
> * backlight driver which is controlled by gmux. The earliest generation
> - * MBP5 2008/09 uses a `TI LP8543`_ backlight driver. All newer models
> - * use a `TI LP8545`_.
> + * MBP5 2008/09 uses a `TI LP8543`_ backlight driver. Newer models
> + * use a `TI LP8545`_ or a TI LP8548.
> *
> * .. _TI LP8543: https://www.ti.com/lit/ds/symlink/lp8543.pdf
> * .. _TI LP8545: https://www.ti.com/lit/ds/symlink/lp8545.pdf
> @@ -302,8 +378,8 @@ static const struct backlight_ops gmux_bl_ops = {
> * connecting it either to the discrete GPU or the Thunderbolt controller.
> * Oddly enough, while the full port is no longer switchable, AUX and HPD
> * are still switchable by way of an `NXP CBTL03062`_ (on pre-retinas
> - * MBP8 2011 and MBP9 2012) or two `TI TS3DS10224`_ (on retinas) under the
> - * control of gmux. Since the integrated GPU is missing the main link,
> + * MBP8 2011 and MBP9 2012) or two `TI TS3DS10224`_ (on pre-t2 retinas) under
> + * the control of gmux. Since the integrated GPU is missing the main link,
> * external displays appear to it as phantoms which fail to link-train.
> *
> * gmux receives the HPD signal of all display connectors and sends an
> @@ -506,6 +582,20 @@ static const struct apple_gmux_config apple_gmux_index = {
> .name = "indexed"
> };
>
> +static const struct apple_gmux_config apple_gmux_mmio = {
> + .read8 = &gmux_mmio_read8,
> + .write8 = &gmux_mmio_write8,
> + .read32 = &gmux_mmio_read32,
> + .write32 = &gmux_mmio_write32,
> + .gmux_handler = &gmux_handler_no_ddc,
> + .handler_flags = VGA_SWITCHEROO_NEEDS_EDP_CONFIG,
> + .resource_type = IORESOURCE_MEM,
> + .read_version_as_u32 = true,
> + .use_acpi_gmsp = true,
> + .name = "T2"
> +};
> +
> +
> /**
> * DOC: Interrupt
> *
> @@ -637,6 +727,25 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
> pnp_set_drvdata(pnp, gmux_data);
>
> switch (type) {
> + case APPLE_GMUX_TYPE_MMIO:
> + gmux_data->config = &apple_gmux_mmio;
> + mutex_init(&gmux_data->index_lock);
> +
> + res = pnp_get_resource(pnp, IORESOURCE_MEM, 0);
> + gmux_data->iostart = res->start;
> + /* Although the ACPI table only allocates 8 bytes, we need 16. */
> + gmux_data->iolen = 16;
> + if (!request_mem_region(gmux_data->iostart, gmux_data->iolen,
> + "Apple gmux")) {
> + pr_err("gmux I/O already in use\n");
> + goto err_free;
> + }
> + gmux_data->iomem_base = ioremap(gmux_data->iostart, gmux_data->iolen);
> + if (!gmux_data->iomem_base) {
> + pr_err("couldn't remap gmux mmio region");
> + goto err_release;
> + }
> + goto get_version;
> case APPLE_GMUX_TYPE_INDEXED:
> gmux_data->config = &apple_gmux_index;
> mutex_init(&gmux_data->index_lock);
> @@ -656,6 +765,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
> goto err_free;
> }
>
> +get_version:
> if (gmux_data->config->read_version_as_u32) {
> version = gmux_read32(gmux_data, GMUX_PORT_VERSION_MAJOR);
> ver_major = (version >> 24) & 0xff;
> @@ -686,7 +796,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
> gmux_data, &gmux_bl_ops, &props);
> if (IS_ERR(bdev)) {
> ret = PTR_ERR(bdev);
> - goto err_release;
> + goto err_unmap;
> }
>
> gmux_data->bdev = bdev;
> @@ -753,7 +863,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
> /*
> * Retina MacBook Pros cannot switch the panel's AUX separately
> * and need eDP pre-calibration. They are distinguishable from
> - * pre-retinas by having an "indexed" gmux.
> + * pre-retinas by having an "indexed" or "T2" gmux.
> *
> * Pre-retina MacBook Pros can switch the panel's DDC separately.
> */
> @@ -778,8 +888,14 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
> &gmux_notify_handler);
> err_notify:
> backlight_device_unregister(bdev);
> +err_unmap:
> + if (gmux_data->iomem_base)
> + iounmap(gmux_data->iomem_base);
> err_release:
> - release_region(gmux_data->iostart, gmux_data->iolen);
> + if (gmux_data->config->resource_type == IORESOURCE_MEM)
> + release_mem_region(gmux_data->iostart, gmux_data->iolen);
> + else
> + release_region(gmux_data->iostart, gmux_data->iolen);
> err_free:
> kfree(gmux_data);
> return ret;
> @@ -800,7 +916,11 @@ static void gmux_remove(struct pnp_dev *pnp)
>
> backlight_device_unregister(gmux_data->bdev);
>
> - release_region(gmux_data->iostart, gmux_data->iolen);
> + if (gmux_data->iomem_base) {
> + iounmap(gmux_data->iomem_base);
> + release_mem_region(gmux_data->iostart, gmux_data->iolen);
> + } else
> + release_region(gmux_data->iostart, gmux_data->iolen);
> apple_gmux_data = NULL;
> kfree(gmux_data);
>
> diff --git a/include/linux/apple-gmux.h b/include/linux/apple-gmux.h
> index 5f658439f7f8..b7532f26b756 100644
> --- a/include/linux/apple-gmux.h
> +++ b/include/linux/apple-gmux.h
> @@ -34,11 +34,18 @@
> #define GMUX_PORT_READ 0xd0
> #define GMUX_PORT_WRITE 0xd4
>
> +#define GMUX_MMIO_PORT_SELECT 0x0e
> +#define GMUX_MMIO_COMMAND_SEND 0x0f
> +
> +#define GMUX_MMIO_READ 0x00
> +#define GMUX_MMIO_WRITE 0x40
> +
> #define GMUX_MIN_IO_LEN (GMUX_PORT_BRIGHTNESS + 4)
>
> enum apple_gmux_type {
> APPLE_GMUX_TYPE_PIO,
> - APPLE_GMUX_TYPE_INDEXED
> + APPLE_GMUX_TYPE_INDEXED,
> + APPLE_GMUX_TYPE_MMIO
> };

With my suggested change to patch 2/5 the - + for APPLE_GMUX_TYPE_INDEXED
will go away because the , is already there. Likewise please add a ,
after APPLE_GMUX_TYPE_MMIO in case we want to add more entries in
the future.

Otherwise this patch looks good to me.

Regards,

Hans

>
> #if IS_ENABLED(CONFIG_APPLE_GMUX)
> @@ -93,19 +100,24 @@ static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, enum apple_gmux_ty
> }
>
> res = pnp_get_resource(pnp_dev, IORESOURCE_IO, 0);
> - if (!res || resource_size(res) < GMUX_MIN_IO_LEN)
> - goto out;
> -
> - /*
> - * Invalid version information may indicate either that the gmux
> - * device isn't present or that it's a new one that uses indexed io.
> - */
> - ver_major = inb(res->start + GMUX_PORT_VERSION_MAJOR);
> - ver_minor = inb(res->start + GMUX_PORT_VERSION_MINOR);
> - ver_release = inb(res->start + GMUX_PORT_VERSION_RELEASE);
> - if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
> - if (apple_gmux_is_indexed(res->start))
> - type = APPLE_GMUX_TYPE_INDEXED;
> + if (res && resource_size(res) >= GMUX_MIN_IO_LEN) {
> + /*
> + * Invalid version information may indicate either that the gmux
> + * device isn't present or that it's a new one that uses indexed io.
> + */
> + ver_major = inb(res->start + GMUX_PORT_VERSION_MAJOR);
> + ver_minor = inb(res->start + GMUX_PORT_VERSION_MINOR);
> + ver_release = inb(res->start + GMUX_PORT_VERSION_RELEASE);
> + if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
> + if (apple_gmux_is_indexed(res->start))
> + type = APPLE_GMUX_TYPE_INDEXED;
> + else
> + goto out;
> + }
> + } else {
> + res = pnp_get_resource(pnp_dev, IORESOURCE_MEM, 0);
> + if (res)
> + type = APPLE_GMUX_TYPE_MMIO;
> else
> goto out;
> }