Message-ID: <8de35754-4f31-1f4d-3a6b-7a56cb5fe162@redhat.com>
Date:   Thu, 16 Feb 2023 14:15:16 +0100
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Subject: Re: [PATCH v2 4/5] apple-gmux: support MMIO gmux on T2 Macs
Content-Language: en-US, nl
To:     Orlando Chamberlain <orlandoch.dev@gmail.com>
Cc:     Mark Gross <markgross@kernel.org>,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org,
        Lukas Wunner <lukas@wunner.de>,
        Seth Forshee <sforshee@kernel.org>,
        Aditya Garg <gargaditya08@live.com>,
        Aun-Ali Zaidi <admin@kodeit.net>,
        Kerem Karabay <kekrby@gmail.com>
References: <20230216122342.5918-1-orlandoch.dev@gmail.com>
 <20230216122342.5918-5-orlandoch.dev@gmail.com>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20230216122342.5918-5-orlandoch.dev@gmail.com>
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Content-Transfer-Encoding: 7bit
Precedence: bulk

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;
>  	}