[PATCH 1/2 v3] drm/pl111: Support the Versatile Express
Robin Murphy
robin.murphy at arm.com
Wed Apr 18 05:48:54 PDT 2018
On 18/04/18 09:52, Linus Walleij wrote:
> The Versatile Express uses a special configuration controller
> deeply embedded in the system motherboard FPGA to multiplex the
> two to three (!) display controller instances out to the single
> SiI9022 bridge.
>
> Set up an extra file with the logic to probe to the FPGA mux
> register on the system controller bus, then parse the device
> tree to see if there is a CLCD or HDLCD instance on the core
> tile (also known as the daughterboard) by looking in the
> root of the device tree for compatible nodes.
>
> - If there is a HDLCD on the core tile, and there is a driver
> for it, we exit probe and deactivate the motherboard CLCD.
> We do not touch the DVI mux in this case, to make sure we
> don't break HDLCD.
>
> - If there is a CLCD on both the motherboard and the core tile
> (only the CA9 has this) the core tile CLCD takes precedence
> and get muxed to the DVI connector.
>
> - Only if there is no working graphics on the core tile, the
> motherboard CLCD is probed and muxed to the DVI connector.
This approach seems reasonable (modulo a couple of nits below), and
almost certainly sufficient for most realistic uses, but I can't help
wondering whether it might be feasible to model the mux with its own
separate connector/bridge driver which could handle prioritisation of
multiple inputs itself (I'm pondering things like RK3288/RK3399 where
the two VOPs feeding into the single HDMI block looks a fair bit like
the V2P-CA9 situation if you squint at it).
> Core tile graphics should always take precedence as it can
> address all memory and is also faster, however the motherboard
> CLCD is good to have around for diagnostics and testing.
>
> It is possible to test the motherboard CLCD by setting the
> status = "disabled" property on the core tile CLCD or
> HDLCD.
>
> Scale down the Versatile Express to 16BPP so we can support a
> 1024x768 display despite the bus bandwidth restrictions on this
> platform. (The motherboard CLCD supports slightly lower
> resolution.)
>
> Cc: Liviu Dudau <liviu.dudau at arm.com>
> Cc: Pawel Moll <pawel.moll at arm.com>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
> ChangeLog v2->v3:
> - Rewrite CLCD detection and mux priority logic, look in
> the device tree root for core tile graphics.
> ChangeLog v1->v2:
> - No changes just reposting rebased on mainline changes.
> ---
> drivers/gpu/drm/pl111/Makefile | 1 +
> drivers/gpu/drm/pl111/pl111_versatile.c | 48 +++++++++++-
> drivers/gpu/drm/pl111/pl111_vexpress.c | 127 ++++++++++++++++++++++++++++++++
> drivers/gpu/drm/pl111/pl111_vexpress.h | 22 ++++++
> 4 files changed, 197 insertions(+), 1 deletion(-)
> create mode 100644 drivers/gpu/drm/pl111/pl111_vexpress.c
> create mode 100644 drivers/gpu/drm/pl111/pl111_vexpress.h
>
> diff --git a/drivers/gpu/drm/pl111/Makefile b/drivers/gpu/drm/pl111/Makefile
> index 9c5e8dba8ac6..19a8189dc54f 100644
> --- a/drivers/gpu/drm/pl111/Makefile
> +++ b/drivers/gpu/drm/pl111/Makefile
> @@ -3,6 +3,7 @@ pl111_drm-y += pl111_display.o \
> pl111_versatile.o \
> pl111_drv.o
>
> +pl111_drm-$(CONFIG_ARCH_VEXPRESS) += pl111_vexpress.o
> pl111_drm-$(CONFIG_DEBUG_FS) += pl111_debugfs.o
>
> obj-$(CONFIG_DRM_PL111) += pl111_drm.o
> diff --git a/drivers/gpu/drm/pl111/pl111_versatile.c b/drivers/gpu/drm/pl111/pl111_versatile.c
> index 9302f516045e..569edf02a36a 100644
> --- a/drivers/gpu/drm/pl111/pl111_versatile.c
> +++ b/drivers/gpu/drm/pl111/pl111_versatile.c
> @@ -1,12 +1,14 @@
> #include <linux/amba/clcd-regs.h>
> #include <linux/device.h>
> #include <linux/of.h>
> +#include <linux/of_platform.h>
> #include <linux/regmap.h>
> #include <linux/mfd/syscon.h>
> #include <linux/bitops.h>
> #include <linux/module.h>
> #include <drm/drmP.h>
> #include "pl111_versatile.h"
> +#include "pl111_vexpress.h"
> #include "pl111_drm.h"
>
> static struct regmap *versatile_syscon_map;
> @@ -22,6 +24,7 @@ enum versatile_clcd {
> REALVIEW_CLCD_PB11MP,
> REALVIEW_CLCD_PBA8,
> REALVIEW_CLCD_PBX,
> + VEXPRESS_CLCD_V2M,
> };
>
> static const struct of_device_id versatile_clcd_of_match[] = {
> @@ -53,6 +56,10 @@ static const struct of_device_id versatile_clcd_of_match[] = {
> .compatible = "arm,realview-pbx-syscon",
> .data = (void *)REALVIEW_CLCD_PBX,
> },
> + {
> + .compatible = "arm,vexpress-muxfpga",
> + .data = (void *)VEXPRESS_CLCD_V2M,
> + },
> {},
> };
>
> @@ -286,12 +293,26 @@ static const struct pl111_variant_data pl111_realview = {
> .fb_bpp = 16,
> };
>
> +/*
> + * Versatile Express PL111 variant, again we just push the maximum
> + * BPP to 16 to be able to get 1024x768 without saturating the memory
> + * bus. The clockdivider also seems broken on the Versatile Express.
> + */
> +static const struct pl111_variant_data pl111_vexpress = {
> + .name = "PL111 Versatile Express",
> + .formats = pl111_realview_pixel_formats,
> + .nformats = ARRAY_SIZE(pl111_realview_pixel_formats),
> + .fb_bpp = 16,
> + .broken_clockdivider = true,
> +};
> +
> int pl111_versatile_init(struct device *dev, struct pl111_drm_dev_private *priv)
> {
> const struct of_device_id *clcd_id;
> enum versatile_clcd versatile_clcd_type;
> struct device_node *np;
> struct regmap *map;
> + int ret;
>
> np = of_find_matching_node_and_match(NULL, versatile_clcd_of_match,
> &clcd_id);
> @@ -301,7 +322,25 @@ int pl111_versatile_init(struct device *dev, struct pl111_drm_dev_private *priv)
> }
> versatile_clcd_type = (enum versatile_clcd)clcd_id->data;
>
> - map = syscon_node_to_regmap(np);
> + /* Versatile Express special handling */
> + if (versatile_clcd_type == VEXPRESS_CLCD_V2M) {
> + struct platform_device *pdev;
> +
> + /* Call into deep Vexpress configuration API */
> + pdev = of_find_device_by_node(np);
Strictly, you should have a platform_device_put(pdev) here.
> + if (!pdev) {
> + dev_err(dev, "can't find the sysreg device, deferring\n");
> + return -EPROBE_DEFER;
> + }
> + map = dev_get_drvdata(&pdev->dev);
> + if (!map) {
> + dev_err(dev, "sysreg has not yet probed\n");
> + return -EPROBE_DEFER;
> + }
> + } else {
> + map = syscon_node_to_regmap(np);
> + }
> +
> if (IS_ERR(map)) {
> dev_err(dev, "no Versatile syscon regmap\n");
> return PTR_ERR(map);
> @@ -340,6 +379,13 @@ int pl111_versatile_init(struct device *dev, struct pl111_drm_dev_private *priv)
> priv->variant_display_disable = pl111_realview_clcd_disable;
> dev_info(dev, "set up callbacks for RealView PL111\n");
> break;
> + case VEXPRESS_CLCD_V2M:
> + priv->variant = &pl111_vexpress;
> + dev_info(dev, "initializing Versatile Express PL111\n");
> + ret = pl111_vexpress_clcd_init(dev, priv, map);
> + if (ret)
> + return ret;
> + break;
> default:
> dev_info(dev, "unknown Versatile system controller\n");
> break;
> diff --git a/drivers/gpu/drm/pl111/pl111_vexpress.c b/drivers/gpu/drm/pl111/pl111_vexpress.c
> new file mode 100644
> index 000000000000..56908027659f
> --- /dev/null
> +++ b/drivers/gpu/drm/pl111/pl111_vexpress.c
> @@ -0,0 +1,127 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Versatile Express PL111 handling
> + * Copyright (C) 2018 Linus Walleij
> + *
> + * This module binds to the "arm,vexpress-muxfpga" device on the
> + * Versatile Express configuration bus and sets up which CLCD instance
> + * gets muxed out on the DVI bridge.
> + */
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/vexpress.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include "pl111_drm.h"
> +#include "pl111_vexpress.h"
> +
> +#define VEXPRESS_FPGAMUX_MOTHERBOARD 0x00
> +#define VEXPRESS_FPGAMUX_DAUGHTERBOARD_1 0x01
> +#define VEXPRESS_FPGAMUX_DAUGHTERBOARD_2 0x02
> +
> +int pl111_vexpress_clcd_init(struct device *dev,
> + struct pl111_drm_dev_private *priv,
> + struct regmap *map)
> +{
> + struct device_node *root;
> + struct device_node *child;
> + struct device_node *ct_clcd = NULL;
> + bool has_coretile_clcd = false;
> + bool has_coretile_hdlcd = false;
> + bool mux_motherboard = true;
> + u32 val;
> + int ret;
> +
> + /*
> + * Check if we have a CLCD or HDLCD on the core tile by checking if a
> + * CLCD or HDLCD is available in the root of the device tree.
> + */
> + root = of_find_node_by_path("/");
> + if (!root)
> + return -EINVAL;
> +
> + for_each_child_of_node(root, child) {
for_each_available_child_of_node()?
Robin.
> + if (of_device_is_compatible(child, "arm,pl111")
> + && of_device_is_available(child)) {
> + has_coretile_clcd = true;
> + ct_clcd = child;
> + break;
> + }
> + if (of_device_is_compatible(child, "arm,hdlcd")
> + && of_device_is_available(child)) {
> + has_coretile_hdlcd = true;
> + break;
> + }
> + }
> +
> + /*
> + * If there is a coretile HDLCD and it has a driver,
> + * do not mux the CLCD on the motherboard to the DVI.
> + */
> + if (has_coretile_hdlcd && IS_ENABLED(CONFIG_DRM_HDLCD))
> + mux_motherboard = false;
> +
> + /*
> + * On the Vexpress CA9 we let the CLCD on the coretile
> + * take precedence, so also in this case do not mux the
> + * motherboard to the DVI.
> + */
> + if (has_coretile_clcd)
> + mux_motherboard = false;
> +
> + if (mux_motherboard) {
> + dev_info(dev, "DVI muxed to motherboard CLCD\n");
> + val = VEXPRESS_FPGAMUX_MOTHERBOARD;
> + } else if (ct_clcd == dev->of_node) {
> + dev_info(dev,
> + "DVI muxed to daughterboard 1 (core tile) CLCD\n");
> + val = VEXPRESS_FPGAMUX_DAUGHTERBOARD_1;
> + } else {
> + dev_info(dev, "core tile graphics present\n");
> + dev_info(dev, "this device will be deactivated\n");
> + return -ENODEV;
> + }
> +
> + ret = regmap_write(map, 0, val);
> + if (ret) {
> + dev_err(dev, "error setting DVI muxmode\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * This sets up the regmap pointer that will then be retrieved by
> + * the detection code in pl111_versatile.c and passed in to the
> + * pl111_vexpress_clcd_init() function above.
> + */
> +static int vexpress_muxfpga_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct regmap *map;
> +
> + map = devm_regmap_init_vexpress_config(&pdev->dev);
> + if (IS_ERR(map))
> + return PTR_ERR(map);
> + dev_set_drvdata(dev, map);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id vexpress_muxfpga_match[] = {
> + { .compatible = "arm,vexpress-muxfpga", }
> +};
> +
> +static struct platform_driver vexpress_muxfpga_driver = {
> + .driver = {
> + .name = "vexpress-muxfpga",
> + .of_match_table = of_match_ptr(vexpress_muxfpga_match),
> + },
> + .probe = vexpress_muxfpga_probe,
> +};
> +
> +module_platform_driver(vexpress_muxfpga_driver);
> diff --git a/drivers/gpu/drm/pl111/pl111_vexpress.h b/drivers/gpu/drm/pl111/pl111_vexpress.h
> new file mode 100644
> index 000000000000..49876417f7b6
> --- /dev/null
> +++ b/drivers/gpu/drm/pl111/pl111_vexpress.h
> @@ -0,0 +1,22 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +struct device;
> +struct pl111_drm_dev_private;
> +struct regmap;
> +
> +#ifdef CONFIG_ARCH_VEXPRESS
> +
> +int pl111_vexpress_clcd_init(struct device *dev,
> + struct pl111_drm_dev_private *priv,
> + struct regmap *map);
> +
> +#else
> +
> +static int inline pl111_vexpress_clcd_init(struct device *dev,
> + struct pl111_drm_dev_private *priv,
> + struct regmap *map)
> +{
> + return -ENODEV;
> +}
> +
> +#endif
>
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