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From: Maxime Ripard <maxime@cerno.tech>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: linux-rpi-kernel@lists.infradead.org,
	bcm-kernel-feedback-list@broadcom.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	Tim Gover <tim.gover@raspberrypi.com>,
	Phil Elwell <phil@raspberrypi.com>,
	Mike Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>,
	linux-clk@vger.kernel.org, Philipp Zabel <p.zabel@pengutronix.de>,
	Maxime Ripard <maxime@cerno.tech>
Subject: [PATCH v5 21/27] clk: bcm: rpi: Discover the firmware clocks
Date: Mon, 15 Jun 2020 10:41:01 +0200
Message-ID: <438d73962741a8c5f7c689319b7443b930a87fde.1592210452.git-series.maxime@cerno.tech> (raw)
In-Reply-To: <cover.98f979c2af2337c57217016d21d7c68e1ac2ce8a.1592210452.git-series.maxime@cerno.tech>

The RaspberryPi4 firmware actually exposes more clocks than are currently
handled by the driver and we will need to change some of them directly
based on the pixel rate for the display related clocks, or the load for the
GPU.

Since the firmware implements DVFS, this rate change can have a number of
side-effects, including adjusting the various PLL voltages or the PLL
parents. The firmware also implements thermal throttling, so even some
thermal pressure can change those parameters behind Linux back.

DVFS is currently implemented on the arm, core, h264, v3d, isp and hevc
clocks, so updating any of them using the MMIO driver (and thus behind the
firmware's back) can lead to troubles, the arm clock obviously being the
most problematic.

In order to make Linux play as nice as possible with those constraints, it
makes sense to rely on the firmware clocks as much as possible. However,
the firmware doesn't seem to provide some equivalents to their MMIO
counterparts, so we can't really replace that driver entirely.

Fortunately, the firmware has an interface to discover the clocks it
exposes.

Let's use it to discover, register the clocks in the clocks framework and
then expose them through the device tree for consumers to use them.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Acked-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/clk/bcm/clk-raspberrypi.c | 153 ++++++++++++++++++++++++++++---
 1 file changed, 141 insertions(+), 12 deletions(-)

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index eebd16040f8a..11a62bde5203 100644
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -296,6 +296,144 @@ static struct clk_hw *raspberrypi_register_pllb_arm(struct raspberrypi_clk *rpi)
 	return &raspberrypi_clk_pllb_arm.hw;
 }
 
+static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
+					      struct clk_rate_request *req)
+{
+	/*
+	 * The firmware will do the rounding but that isn't part of
+	 * the interface with the firmware, so we just do our best
+	 * here.
+	 */
+	req->rate = clamp(req->rate, req->min_rate, req->max_rate);
+	return 0;
+}
+
+static const struct clk_ops raspberrypi_firmware_clk_ops = {
+	.is_prepared	= raspberrypi_fw_is_prepared,
+	.recalc_rate	= raspberrypi_fw_get_rate,
+	.determine_rate	= raspberrypi_fw_dumb_determine_rate,
+	.set_rate	= raspberrypi_fw_set_rate,
+};
+
+static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
+					       unsigned int parent,
+					       unsigned int id)
+{
+	struct raspberrypi_clk_data *data;
+	struct clk_init_data init = {};
+	u32 min_rate, max_rate;
+	int ret;
+
+	if (id == RPI_FIRMWARE_ARM_CLK_ID) {
+		struct clk_hw *hw;
+
+		hw = raspberrypi_register_pllb(rpi);
+		if (IS_ERR(hw)) {
+			dev_err(rpi->dev, "Failed to initialize pllb, %ld\n",
+				PTR_ERR(hw));
+			return hw;
+		}
+
+		return raspberrypi_register_pllb_arm(rpi);
+	}
+
+	data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+	data->rpi = rpi;
+	data->id = id;
+
+	init.name = devm_kasprintf(rpi->dev, GFP_KERNEL, "fw-clk-%u", id);
+	init.ops = &raspberrypi_firmware_clk_ops;
+	init.flags = CLK_GET_RATE_NOCACHE;
+
+	data->hw.init = &init;
+
+	ret = raspberrypi_clock_property(rpi->firmware, data,
+					 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
+					 &min_rate);
+	if (ret) {
+		dev_err(rpi->dev, "Failed to get clock %d min freq: %d",
+			id, ret);
+		return ERR_PTR(ret);
+	}
+
+	ret = raspberrypi_clock_property(rpi->firmware, data,
+					 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
+					 &max_rate);
+	if (ret) {
+		dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
+			id, ret);
+		return ERR_PTR(ret);
+	}
+
+	ret = devm_clk_hw_register(rpi->dev, &data->hw);
+	if (ret)
+		return ERR_PTR(ret);
+
+	clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
+
+	if (id == RPI_FIRMWARE_ARM_CLK_ID) {
+		ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
+						  NULL, "cpu0");
+		if (ret) {
+			dev_err(rpi->dev, "Failed to initialize clkdev\n");
+			return ERR_PTR(ret);
+		}
+	}
+
+	return &data->hw;
+}
+
+struct rpi_firmware_get_clocks_response {
+	u32 parent;
+	u32 id;
+};
+
+static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
+				       struct clk_hw_onecell_data *data)
+{
+	struct rpi_firmware_get_clocks_response *clks;
+	int ret;
+
+	clks = devm_kcalloc(rpi->dev,
+			    sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID,
+			    GFP_KERNEL);
+	if (!clks)
+		return -ENOMEM;
+
+	ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
+				    clks,
+				    sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
+	if (ret)
+		return ret;
+
+	while (clks->id) {
+		struct clk_hw *hw;
+
+		switch (clks->id) {
+		case RPI_FIRMWARE_ARM_CLK_ID:
+		case RPI_FIRMWARE_CORE_CLK_ID:
+		case RPI_FIRMWARE_M2MC_CLK_ID:
+		case RPI_FIRMWARE_V3D_CLK_ID:
+			hw = raspberrypi_clk_register(rpi, clks->parent,
+						      clks->id);
+			if (IS_ERR(hw))
+				return PTR_ERR(hw);
+
+			data->hws[clks->id] = hw;
+			data->num = clks->id + 1;
+			fallthrough;
+
+		default:
+			clks++;
+			break;
+		}
+	}
+
+	return 0;
+}
+
 static int raspberrypi_clk_probe(struct platform_device *pdev)
 {
 	struct clk_hw_onecell_data *clk_data;
@@ -303,7 +441,6 @@ static int raspberrypi_clk_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct rpi_firmware *firmware;
 	struct raspberrypi_clk *rpi;
-	struct clk_hw *hw;
 	int ret;
 
 	/*
@@ -340,17 +477,9 @@ static int raspberrypi_clk_probe(struct platform_device *pdev)
 	if (!clk_data)
 		return -ENOMEM;
 
-	hw = raspberrypi_register_pllb(rpi);
-	if (IS_ERR(hw)) {
-		dev_err(dev, "Failed to initialize pllb, %ld\n", PTR_ERR(hw));
-		return PTR_ERR(hw);
-	}
-
-	hw = raspberrypi_register_pllb_arm(rpi);
-	if (IS_ERR(hw))
-		return PTR_ERR(hw);
-	clk_data->hws[RPI_FIRMWARE_ARM_CLK_ID] = hw;
-	clk_data->num = RPI_FIRMWARE_ARM_CLK_ID + 1;
+	ret = raspberrypi_discover_clocks(rpi, clk_data);
+	if (ret)
+		return ret;
 
 	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
 					  clk_data);
-- 
git-series 0.9.1

  parent reply index

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15  8:40 [PATCH v5 00/27] clk: bcm: rpi: Add support for BCM2711 " Maxime Ripard
2020-06-15  8:40 ` [PATCH v5 01/27] dt-bindings: arm: bcm: Convert BCM2835 firmware binding to YAML Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 02/27] dt-bindings: clock: Add a binding for the RPi Firmware clocks Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 03/27] firmware: rpi: Only create clocks device if we don't have a node for it Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 04/27] clk: bcm: rpi: Allow the driver to be probed by DT Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 05/27] clk: bcm: rpi: Statically init clk_init_data Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 06/27] clk: bcm: rpi: Use clk_hw_register for pllb_arm Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 07/27] clk: bcm: rpi: Remove global pllb_arm clock pointer Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 08/27] clk: bcm: rpi: Make sure pllb_arm is removed Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 09/27] clk: bcm: rpi: Remove pllb_arm_lookup global pointer Maxime Ripard
2020-06-25  0:42   ` Stephen Boyd
2020-06-25  0:44   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 10/27] clk: bcm: rpi: Switch to clk_hw_register_clkdev Maxime Ripard
2020-06-25  0:44   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 11/27] clk: bcm: rpi: Make sure the clkdev lookup is removed Maxime Ripard
2020-06-25  0:44   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 12/27] clk: bcm: rpi: Use CCF boundaries instead of rolling our own Maxime Ripard
2020-06-25  0:44   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 13/27] clk: bcm: rpi: Create a data structure for the clocks Maxime Ripard
2020-06-25  0:44   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 14/27] clk: bcm: rpi: Add clock id to data Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 15/27] clk: bcm: rpi: Pass the clocks data to the firmware function Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 16/27] clk: bcm: rpi: Rename is_prepared function Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 17/27] clk: bcm: rpi: Split pllb clock hooks Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 18/27] clk: bcm: rpi: Make the PLLB registration function return a clk_hw Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:40 ` [PATCH v5 19/27] clk: bcm: rpi: Add DT provider for the clocks Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 20/27] clk: bcm: rpi: Add an enum for the firmware clocks Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:41 ` Maxime Ripard [this message]
2020-06-25  0:45   ` [PATCH v5 21/27] clk: bcm: rpi: Discover " Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 22/27] clk: bcm: rpi: Give firmware clocks a name Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 23/27] Revert "clk: bcm2835: remove pllb" Maxime Ripard
2020-06-25  0:45   ` Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 24/27] ARM: dts: bcm2711: Add firmware clocks node Maxime Ripard
2020-06-25  8:16   ` Nicolas Saenz Julienne
2020-06-15  8:41 ` [PATCH v5 25/27] clk: bcm2835: Allow custom CCF flags for the PLLs Maxime Ripard
2020-06-25  0:46   ` Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 26/27] clk: bcm2835: Don't cache the PLLB rate Maxime Ripard
2020-06-25  0:46   ` Stephen Boyd
2020-06-15  8:41 ` [PATCH v5 27/27] clk: bcm: rpi: Remove the quirks for the CPU clock Maxime Ripard
2020-06-25  0:46   ` Stephen Boyd
2020-06-19  9:37 ` [PATCH v5 00/27] clk: bcm: rpi: Add support for BCM2711 firmware clocks Stephen Boyd
2020-06-19  9:44   ` Nicolas Saenz Julienne
2020-06-19 23:57     ` Stephen Boyd
2020-06-20  0:20       ` Stephen Boyd
2020-06-25  0:40         ` Stephen Boyd
2020-06-19 11:52   ` Maxime Ripard
2020-06-19 23:57     ` Stephen Boyd
2020-06-25  1:15 ` Stephen Boyd

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