@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/clk.h>
+#include <linux/of_clk.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
@@ -190,6 +192,12 @@ struct simpledrm_device {
struct drm_device dev;
struct platform_device *pdev;
+ /* clocks */
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+ unsigned int clk_count;
+ struct clk **clks;
+#endif
+
/* simplefb settings */
struct drm_display_mode mode;
const struct drm_format_info *format;
@@ -211,6 +219,103 @@ static struct simpledrm_device *simpledrm_device_of_dev(struct drm_device *dev)
return container_of(dev, struct simpledrm_device, dev);
}
+/*
+ * Hardware
+ */
+
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+/*
+ * Clock handling code.
+ *
+ * Here we handle the clocks property of our "simple-framebuffer" dt node.
+ * This is necessary so that we can make sure that any clocks needed by
+ * the display engine 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 clocks.
+ *
+ * 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 clock 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_clocks(void *res)
+{
+ struct simpledrm_device *sdev = simpledrm_device_of_dev(res);
+ unsigned int i;
+
+ for (i = 0; i < sdev->clk_count; ++i) {
+ if (sdev->clks[i]) {
+ clk_disable_unprepare(sdev->clks[i]);
+ clk_put(sdev->clks[i]);
+ }
+ }
+}
+
+static int simpledrm_device_init_clocks(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 clk *clock;
+ unsigned int i;
+ int ret;
+
+ if (dev_get_platdata(&pdev->dev) || !of_node)
+ return 0;
+
+ sdev->clk_count = of_clk_get_parent_count(of_node);
+ if (!sdev->clk_count)
+ return 0;
+
+ sdev->clks = drmm_kzalloc(dev, sdev->clk_count * sizeof(sdev->clks[0]),
+ GFP_KERNEL);
+ if (!sdev->clks)
+ return -ENOMEM;
+
+ for (i = 0; i < sdev->clk_count; ++i) {
+ clock = of_clk_get(of_node, i);
+ if (IS_ERR(clock)) {
+ ret = PTR_ERR(clock);
+ if (ret == -EPROBE_DEFER)
+ goto err;
+ drm_err(dev, "clock %u not found: %d\n", i, ret);
+ continue;
+ }
+ ret = clk_prepare_enable(clock);
+ if (ret) {
+ drm_err(dev, "failed to enable clock %u: %d\n",
+ i, ret);
+ clk_put(clock);
+ }
+ sdev->clks[i] = clock;
+ }
+
+ return devm_add_action_or_reset(&pdev->dev,
+ simpledrm_device_release_clocks,
+ sdev);
+
+err:
+ while (i) {
+ --i;
+ if (sdev->clks[i]) {
+ clk_disable_unprepare(sdev->clks[i]);
+ clk_put(sdev->clks[i]);
+ }
+ }
+ return ret;
+}
+#else
+static int simpledrm_device_init_clocks(struct simpledrm_device *sdev)
+{
+ return 0;
+}
+#endif
+
/*
* Simplefb settings
*/
@@ -552,6 +657,9 @@ simpledrm_device_create(struct drm_driver *drv, struct platform_device *pdev)
sdev->pdev = pdev;
platform_set_drvdata(pdev, sdev);
+ ret = simpledrm_device_init_clocks(sdev);
+ if (ret)
+ return ERR_PTR(ret);
ret = simpledrm_device_init_fb(sdev);
if (ret)
return ERR_PTR(ret);