Linux-Doc Archive on lore.kernel.org
 help / color / Atom feed
From: Thomas Zimmermann <tzimmermann@suse.de>
To: daniel@ffwll.ch, airlied@linux.ie,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	kraxel@redhat.com, corbet@lwn.net, lgirdwood@gmail.com,
	broonie@kernel.org, sam@ravnborg.org, robh@kernel.org,
	emil.l.velikov@gmail.com, geert+renesas@glider.be,
	hdegoede@redhat.com, bluescreen_avenger@verizon.net,
	gregkh@linuxfoundation.org
Cc: dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Thomas Zimmermann <tzimmermann@suse.de>
Subject: [PATCH v4 8/9] drm/simpledrm: Acquire regulators from DT device node
Date: Fri, 16 Apr 2021 11:00:47 +0200
Message-ID: <20210416090048.11492-9-tzimmermann@suse.de> (raw)
In-Reply-To: <20210416090048.11492-1-tzimmermann@suse.de>

Make sure required hardware regulators are enabled while the firmware
framebuffer is in use.

The basic code has been taken from the simplefb driver and adapted
to DRM. Regulators are released automatically via devres helpers.

v2:
	* use strscpy()

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: nerdopolis <bluescreen_avenger@verizon.net>
---
 drivers/gpu/drm/tiny/simpledrm.c | 128 +++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 996318500abf..9d522473cd7c 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -4,6 +4,7 @@
 #include <linux/of_clk.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
 
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_connector.h>
@@ -197,6 +198,11 @@ struct simpledrm_device {
 	unsigned int clk_count;
 	struct clk **clks;
 #endif
+	/* regulators */
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+	unsigned int regulator_count;
+	struct regulator **regulators;
+#endif
 
 	/* simplefb settings */
 	struct drm_display_mode mode;
@@ -316,6 +322,125 @@ static int simpledrm_device_init_clocks(struct simpledrm_device *sdev)
 }
 #endif
 
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+
+#define SUPPLY_SUFFIX "-supply"
+
+/*
+ * Regulator handling code.
+ *
+ * Here we handle the num-supplies and vin*-supply properties of our
+ * "simple-framebuffer" dt node. This is necessary so that we can make sure
+ * that any regulators needed by the display hardware that the bootloader
+ * set up for us (and for which it provided a simplefb dt node), stay up,
+ * for the life of the simplefb driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the
+ * regulators.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the regulator definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+
+static void simpledrm_device_release_regulators(void *res)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(res);
+	unsigned int i;
+
+	for (i = 0; i < sdev->regulator_count; ++i) {
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+}
+
+static int simpledrm_device_init_regulators(struct simpledrm_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = sdev->pdev;
+	struct device_node *of_node = pdev->dev.of_node;
+	struct property *prop;
+	struct regulator *regulator;
+	const char *p;
+	unsigned int count = 0, i = 0;
+	int ret;
+
+	if (dev_get_platdata(&pdev->dev) || !of_node)
+		return 0;
+
+	/* Count the number of regulator supplies */
+	for_each_property_of_node(of_node, prop) {
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (p && p != prop->name)
+			++count;
+	}
+
+	if (!count)
+		return 0;
+
+	sdev->regulators = drmm_kzalloc(dev,
+					count * sizeof(sdev->regulators[0]),
+					GFP_KERNEL);
+	if (!sdev->regulators)
+		return -ENOMEM;
+
+	for_each_property_of_node(of_node, prop) {
+		char name[32]; /* 32 is max size of property name */
+		size_t len;
+
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (!p || p == prop->name)
+			continue;
+		len = strlen(prop->name) - strlen(SUPPLY_SUFFIX) + 1;
+		strscpy(name, prop->name, min(sizeof(name), len));
+
+		regulator = regulator_get_optional(&pdev->dev, name);
+		if (IS_ERR(regulator)) {
+			ret = PTR_ERR(regulator);
+			if (ret == -EPROBE_DEFER)
+				goto err;
+			drm_err(dev, "regulator %s not found: %d\n",
+				name, ret);
+			continue;
+		}
+
+		ret = regulator_enable(regulator);
+		if (ret) {
+			drm_err(dev, "failed to enable regulator %u: %d\n",
+				i, ret);
+			regulator_put(regulator);
+		}
+
+		sdev->regulators[i++] = regulator;
+	}
+	sdev->regulator_count = i;
+
+	return devm_add_action_or_reset(&pdev->dev,
+					simpledrm_device_release_regulators,
+					sdev);
+
+err:
+	while (i) {
+		--i;
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+	return ret;
+}
+#else
+static int simpledrm_device_init_regulators(struct simpledrm_device *sdev)
+{
+	return 0;
+}
+#endif
+
 /*
  *  Simplefb settings
  */
@@ -658,6 +783,9 @@ simpledrm_device_create(struct drm_driver *drv, struct platform_device *pdev)
 	platform_set_drvdata(pdev, sdev);
 
 	ret = simpledrm_device_init_clocks(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simpledrm_device_init_regulators(sdev);
 	if (ret)
 		return ERR_PTR(ret);
 	ret = simpledrm_device_init_fb(sdev);
-- 
2.31.1


  parent reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16  9:00 [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip() Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 2/9] drm/format-helper: Add blitter functions Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 3/9] drm/aperture: Add infrastructure for aperture ownership Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 4/9] drm: Add simpledrm driver Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 5/9] drm/simpledrm: Add fbdev emulation Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 6/9] drm/simpledrm: Initialize framebuffer data from device-tree node Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 7/9] drm/simpledrm: Acquire clocks from DT device node Thomas Zimmermann
2021-04-16  9:00 ` Thomas Zimmermann [this message]
2021-04-16  9:00 ` [PATCH v4 9/9] drm/simpledrm: Acquire memory aperture for framebuffer Thomas Zimmermann
2021-04-19  8:00 ` [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs Geert Uytterhoeven
2021-04-20  8:46   ` Daniel Vetter
2021-04-20  9:16     ` Geert Uytterhoeven
2021-04-20 11:11       ` Daniel Vetter
2021-04-20  9:22     ` Gerd Hoffmann
2021-04-20  9:27       ` Geert Uytterhoeven
2021-04-26 12:22         ` Thomas Zimmermann
2021-04-26 19:05           ` Geert Uytterhoeven
2021-04-26 12:18     ` Thomas Zimmermann
2021-04-26 15:08       ` Daniel Vetter
2021-04-29 10:24 ` Maxime Ripard

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210416090048.11492-9-tzimmermann@suse.de \
    --to=tzimmermann@suse.de \
    --cc=airlied@linux.ie \
    --cc=bluescreen_avenger@verizon.net \
    --cc=broonie@kernel.org \
    --cc=corbet@lwn.net \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=emil.l.velikov@gmail.com \
    --cc=geert+renesas@glider.be \
    --cc=gregkh@linuxfoundation.org \
    --cc=hdegoede@redhat.com \
    --cc=kraxel@redhat.com \
    --cc=lgirdwood@gmail.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=maarten.lankhorst@linux.intel.com \
    --cc=mripard@kernel.org \
    --cc=robh@kernel.org \
    --cc=sam@ravnborg.org \
    --cc=virtualization@lists.linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Doc Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-doc/0 linux-doc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-doc linux-doc/ https://lore.kernel.org/linux-doc \
		linux-doc@vger.kernel.org
	public-inbox-index linux-doc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-doc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git