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Date: Mon, 13 Feb 2023 17:29:54 +0530
From: Aradhya Bhatia <a-bhatia1@...com>
To: Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Santosh Shilimkar <ssantosh@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
CC: Tomi Valkeinen <tomba@...nel.org>,
Samuel Holland <samuel@...lland.org>,
Linux Clock List <linux-clk@...r.kernel.org>,
Devicetree List <devicetree@...r.kernel.org>,
Linux Kernel List <linux-kernel@...r.kernel.org>,
Nishanth Menon <nm@...com>,
Vignesh Raghavendra <vigneshr@...com>,
Devarsh Thakkar <devarsht@...com>,
Jai Luthra <j-luthra@...com>, Aradhya Bhatia <a-bhatia1@...com>
Subject: [PATCH v2 2/2] clk: keystone: Add support AM62 DSS clock divider
On TI's AM62 Family of SoCs, the pixel frequency of the DSS Video Port 0
comes from a by-7 clock divider. This is done to support the clock for
OLDI transmitters that need serial clock 7 times the pixel frequency.
A clock set request on this clock, is forwarded to its parent clock by
default, using the SET_RATE_PARENT flag. The PLL (in this case the
parent) generates serial clock for OLDI, which is then also fed to DSS
using this clock divider.
Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
---
drivers/clk/keystone/Kconfig | 9 ++
drivers/clk/keystone/Makefile | 1 +
drivers/clk/keystone/clk-am62-dss.c | 164 ++++++++++++++++++++++++++++
3 files changed, 174 insertions(+)
create mode 100644 drivers/clk/keystone/clk-am62-dss.c
diff --git a/drivers/clk/keystone/Kconfig b/drivers/clk/keystone/Kconfig
index e64d6726048f..543314ddfd2c 100644
--- a/drivers/clk/keystone/Kconfig
+++ b/drivers/clk/keystone/Kconfig
@@ -34,3 +34,12 @@ config TI_SYSCON_CLK
help
This adds clock driver support for syscon based gate
clocks on TI's K2 and K3 SoCs.
+
+config TI_AM62_DSS_CLK
+ tristate "Clock Divider for DSS VP0 of AM62 Family of SoCs"
+ depends on ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
+ default TI_SCI_CLK
+ help
+ This adds clock divider driver support for Video Port 0 of Display
+ SubSystems (DSS) under AM62 Family of SoCs. This clock divider
+ forwards a seventh (1/7) of the incoming clock.
diff --git a/drivers/clk/keystone/Makefile b/drivers/clk/keystone/Makefile
index 0e426e648f7c..3a683d622a60 100644
--- a/drivers/clk/keystone/Makefile
+++ b/drivers/clk/keystone/Makefile
@@ -2,3 +2,4 @@
obj-$(CONFIG_COMMON_CLK_KEYSTONE) += pll.o gate.o
obj-$(CONFIG_TI_SCI_CLK) += sci-clk.o
obj-$(CONFIG_TI_SYSCON_CLK) += syscon-clk.o
+obj-$(CONFIG_TI_AM62_DSS_CLK) += clk-am62-dss.o
diff --git a/drivers/clk/keystone/clk-am62-dss.c b/drivers/clk/keystone/clk-am62-dss.c
new file mode 100644
index 000000000000..2c9fc4bc89e3
--- /dev/null
+++ b/drivers/clk/keystone/clk-am62-dss.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+ */
+#include <linux/module.h>
+#include <linux/clk-provider.h>
+#include <linux/platform_device.h>
+
+struct ti_am62_dss_clk {
+ struct clk_hw hw;
+ unsigned int div;
+};
+
+#define to_ti_am62_dss_clk(_hw) \
+ container_of(_hw, struct ti_am62_dss_clk, hw)
+
+static unsigned long ti_am62_dss_clk_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct ti_am62_dss_clk *priv = to_ti_am62_dss_clk(hw);
+ unsigned long rate;
+
+ rate = parent_rate;
+ do_div(rate, priv->div);
+ return (unsigned long)rate;
+}
+
+static long ti_am62_dss_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ struct ti_am62_dss_clk *priv = to_ti_am62_dss_clk(hw);
+
+ if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
+ unsigned long best_parent;
+
+ best_parent = rate * priv->div;
+ *prate = clk_hw_round_rate(clk_hw_get_parent(hw), best_parent);
+ }
+
+ return (*prate / priv->div);
+}
+
+static int ti_am62_dss_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ /*
+ * We must report success but we can do so unconditionally because
+ * ti_am62_dss_clk_round_rate returns values that ensure this call is a
+ * nop.
+ */
+
+ return 0;
+}
+
+static const struct clk_ops ti_am62_dss_clk_ops = {
+ .round_rate = ti_am62_dss_clk_round_rate,
+ .set_rate = ti_am62_dss_clk_set_rate,
+ .recalc_rate = ti_am62_dss_clk_recalc_rate,
+};
+
+static struct clk_hw *
+clk_hw_register_am62_dss_clk(struct device *dev, const char *name,
+ unsigned long flags, unsigned int div)
+{
+ struct ti_am62_dss_clk *priv;
+ struct clk_init_data init = { };
+ struct clk_parent_data pdata = { .index = 0 };
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return ERR_PTR(-ENOMEM);
+
+ /* struct ti_am62_dss_clk assignments */
+ priv->div = div;
+ priv->hw.init = &init;
+
+ init.name = name;
+ init.ops = &ti_am62_dss_clk_ops;
+ init.flags = flags;
+ init.parent_names = NULL;
+ init.parent_data = &pdata;
+ init.num_parents = 1;
+
+ ret = devm_clk_hw_register(dev, &priv->hw);
+ if (ret)
+ return ERR_PTR(ret);
+
+ return &priv->hw;
+}
+
+static void clk_hw_unregister_am62_dss_clk(struct clk_hw *hw)
+{
+ struct ti_am62_dss_clk *priv;
+
+ priv = to_ti_am62_dss_clk(hw);
+
+ clk_hw_unregister(hw);
+ kfree(priv);
+}
+
+static int ti_am62_dss_clk_remove(struct platform_device *pdev)
+{
+ struct clk_hw *hw = platform_get_drvdata(pdev);
+
+ of_clk_del_provider(pdev->dev.of_node);
+ clk_hw_unregister_am62_dss_clk(hw);
+
+ return 0;
+}
+
+static int ti_am62_dss_clk_probe(struct platform_device *pdev)
+{
+ struct clk_hw *hw;
+ const char *clk_name = pdev->name;
+ struct device *dev = &pdev->dev;
+ unsigned long flags = 0;
+ u32 div;
+ int ret;
+
+ if (of_property_read_u32(dev->of_node, "clock-div", &div)) {
+ dev_err(dev, "%s: TI AM62 DSS clock must have a clock-div property.\n",
+ __func__);
+ return -EIO;
+ }
+
+ flags |= CLK_SET_RATE_PARENT;
+
+ hw = clk_hw_register_am62_dss_clk(dev, clk_name, flags, div);
+ if (IS_ERR(hw)) {
+ dev_err(dev, "%s: failed to register %s\n", __func__, clk_name);
+ return PTR_ERR(hw);
+ }
+
+ ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
+ if (ret) {
+ clk_hw_unregister_am62_dss_clk(hw);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, hw);
+
+ return 0;
+}
+
+static const struct of_device_id ti_am62_dss_clk_ids[] = {
+ { .compatible = "ti,am62-dss-vp0-div-clk" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ti_am62_dss_clk_ids);
+
+static struct platform_driver ti_am62_dss_clk_driver = {
+ .driver = {
+ .name = "ti_am62_dss_clk",
+ .of_match_table = ti_am62_dss_clk_ids,
+ },
+ .probe = ti_am62_dss_clk_probe,
+ .remove = ti_am62_dss_clk_remove,
+};
+module_platform_driver(ti_am62_dss_clk_driver);
+
+MODULE_AUTHOR("Aradhya Bhatia <a-bhatia1@...com>");
+MODULE_DESCRIPTION("TI AM62 DSS - OLDI Fixed Clock Divider driver");
+MODULE_LICENSE("GPL");
--
2.39.1
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