[PATCH 2/3] clk: rockchip: Add linked gate clock support

[Alexander Shiyan <eagle.alexander923@gmail.com>]

Recent Rockchip SoCs have a new hardware block called Native Interface
Unit (NIU), which gates clocks to devices behind them. These clock
gates will only have a running output clock when all of the following
conditions are met:

1. the parent clock is enabled
2. the enable bit is set correctly
3. the linked clock is enabled

To handle them this code registers them as a normal gate type clock,
which takes care of condition 1 + 2. Thus the complete handling
of these clocks has been moved into its own driver.

Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
---
 drivers/clk/rockchip/Makefile    |  1 +
 drivers/clk/rockchip/clk.c       | 67 ++++++++++++++++++++++++++------
 drivers/clk/rockchip/clk.h       | 25 +++++++++++-
 drivers/clk/rockchip/gate-link.c | 44 +++++++++++++++++++++
 4 files changed, 123 insertions(+), 14 deletions(-)
 create mode 100644 drivers/clk/rockchip/gate-link.c

diff --git a/drivers/clk/rockchip/Makefile b/drivers/clk/rockchip/Makefile
index 8d752d11b9..b1ab402003 100644
--- a/drivers/clk/rockchip/Makefile
+++ b/drivers/clk/rockchip/Makefile
@@ -12,6 +12,7 @@ clk-rockchip-y += clk-inverter.o
 clk-rockchip-y += clk-mmc-phase.o
 clk-rockchip-y += clk-muxgrf.o
 clk-rockchip-y += clk-ddr.o
+clk-rockchip-y += gate-link.o
 
 clk-rockchip-$(CONFIG_RESET_CONTROLLER) += softrst.o
 
diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
index 127b79e2c8..b162ca9798 100644
--- a/drivers/clk/rockchip/clk.c
+++ b/drivers/clk/rockchip/clk.c
@@ -240,7 +240,7 @@ static struct clk *rockchip_clk_register_frac_branch(
 			return mux_clk;
 		}
 
-		rockchip_clk_add_lookup(ctx, mux_clk, child->id);
+		rockchip_clk_set_lookup(ctx, mux_clk, child->id);
 
 		/* notifier on the fraction divider to catch rate changes */
 		if (frac->mux_frac_idx >= 0) {
@@ -350,14 +350,6 @@ void rockchip_clk_of_add_provider(struct device_node *np,
 }
 EXPORT_SYMBOL_GPL(rockchip_clk_of_add_provider);
 
-void rockchip_clk_add_lookup(struct rockchip_clk_provider *ctx,
-			     struct clk *clk, unsigned int id)
-{
-	if (ctx->clk_data.clks && id)
-		ctx->clk_data.clks[id] = clk;
-}
-EXPORT_SYMBOL_GPL(rockchip_clk_add_lookup);
-
 void rockchip_clk_register_plls(struct rockchip_clk_provider *ctx,
 				struct rockchip_pll_clock *list,
 				unsigned int nr_pll, int grf_lock_offset)
@@ -378,7 +370,7 @@ void rockchip_clk_register_plls(struct rockchip_clk_provider *ctx,
 			continue;
 		}
 
-		rockchip_clk_add_lookup(ctx, clk, list->id);
+		rockchip_clk_set_lookup(ctx, clk, list->id);
 	}
 }
 EXPORT_SYMBOL_GPL(rockchip_clk_register_plls);
@@ -400,6 +392,29 @@ unsigned long rockchip_clk_find_max_clk_id(struct rockchip_clk_branch *list,
 }
 EXPORT_SYMBOL_GPL(rockchip_clk_find_max_clk_id);
 
+static struct device *rockchip_clk_register_gate_link(
+		struct device *parent_dev,
+		struct rockchip_clk_provider *ctx,
+		struct rockchip_clk_branch *clkbr)
+{
+	struct rockchip_gate_link_platdata gate_link_pdata = {
+		.ctx = ctx,
+		.clkbr = clkbr,
+	};
+	struct device *dev;
+	int ret;
+
+	dev = device_alloc("rockchip-gate-link-clk", clkbr->id);
+	dev->parent = parent_dev;
+	dev->platform_data = &gate_link_pdata;
+
+	ret = platform_device_register(dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return dev;
+}
+
 void rockchip_clk_register_branches(struct rockchip_clk_provider *ctx,
 				    struct rockchip_clk_branch *list,
 				    unsigned int nr_clk)
@@ -505,6 +520,9 @@ void rockchip_clk_register_branches(struct rockchip_clk_provider *ctx,
 				list->div_width, list->div_flags,
 				ctx->reg_base, &ctx->lock);
 			break;
+		case branch_linked_gate:
+			/* must be registered late, fall-through for error message */
+			break;
 		}
 
 		/* none of the cases above matched */
@@ -520,11 +538,36 @@ void rockchip_clk_register_branches(struct rockchip_clk_provider *ctx,
 			continue;
 		}
 
-		rockchip_clk_add_lookup(ctx, clk, list->id);
+		rockchip_clk_set_lookup(ctx, clk, list->id);
 	}
 }
 EXPORT_SYMBOL_GPL(rockchip_clk_register_branches);
 
+void rockchip_clk_register_late_branches(struct device *dev,
+					 struct rockchip_clk_provider *ctx,
+					 struct rockchip_clk_branch *list,
+					 unsigned int nr_clk)
+{
+	unsigned int idx;
+
+	for (idx = 0; idx < nr_clk; idx++, list++) {
+		struct device *pdev = NULL;
+
+		switch (list->branch_type) {
+		case branch_linked_gate:
+			pdev = rockchip_clk_register_gate_link(dev, ctx, list);
+			break;
+		default:
+			dev_err(dev, "unknown clock type %d\n", list->branch_type);
+			break;
+		}
+
+		if (!pdev)
+			dev_err(dev, "failed to register device for clock %s\n", list->name);
+	}
+}
+EXPORT_SYMBOL_GPL(rockchip_clk_register_late_branches);
+
 void rockchip_clk_register_armclk(struct rockchip_clk_provider *ctx,
 				  unsigned int lookup_id,
 				  const char *name, const char *const *parent_names,
@@ -544,7 +587,7 @@ void rockchip_clk_register_armclk(struct rockchip_clk_provider *ctx,
 		return;
 	}
 
-	rockchip_clk_add_lookup(ctx, clk, lookup_id);
+	rockchip_clk_set_lookup(ctx, clk, lookup_id);
 }
 EXPORT_SYMBOL_GPL(rockchip_clk_register_armclk);
 
diff --git a/drivers/clk/rockchip/clk.h b/drivers/clk/rockchip/clk.h
index 6665f8ac90..d201e753ef 100644
--- a/drivers/clk/rockchip/clk.h
+++ b/drivers/clk/rockchip/clk.h
@@ -500,6 +500,7 @@ enum rockchip_clk_branch_type {
 	branch_divider,
 	branch_fraction_divider,
 	branch_gate,
+	branch_linked_gate,
 	branch_mmc,
 	branch_inverter,
 	branch_factor,
@@ -883,17 +884,37 @@ struct rockchip_clk_branch {
 #define SGRF_GATE(_id, cname, pname)				\
 		FACTOR(_id, cname, pname, 0, 1, 1)
 
+static inline struct clk *rockchip_clk_get_lookup(struct rockchip_clk_provider *ctx,
+						  unsigned int id)
+{
+	return ctx->clk_data.clks[id];
+}
+
+static inline void rockchip_clk_set_lookup(struct rockchip_clk_provider *ctx,
+					   struct clk *clk, unsigned int id)
+{
+	ctx->clk_data.clks[id] = clk;
+}
+
+struct rockchip_gate_link_platdata {
+	struct rockchip_clk_provider *ctx;
+	struct rockchip_clk_branch *clkbr;
+};
+
 struct rockchip_clk_provider *rockchip_clk_init(struct device_node *np,
 			void __iomem *base, unsigned long nr_clks);
 void rockchip_clk_of_add_provider(struct device_node *np,
 				struct rockchip_clk_provider *ctx);
-void rockchip_clk_add_lookup(struct rockchip_clk_provider *ctx,
-			     struct clk *clk, unsigned int id);
 unsigned long rockchip_clk_find_max_clk_id(struct rockchip_clk_branch *list,
 					   unsigned int nr_clk);
 void rockchip_clk_register_branches(struct rockchip_clk_provider *ctx,
 				    struct rockchip_clk_branch *list,
 				    unsigned int nr_clk);
+void rockchip_clk_register_late_branches(struct device *dev,
+					 struct rockchip_clk_provider *ctx,
+					 struct rockchip_clk_branch *list,
+					 unsigned int nr_clk);
+
 void rockchip_clk_register_plls(struct rockchip_clk_provider *ctx,
 				struct rockchip_pll_clock *pll_list,
 				unsigned int nr_pll, int grf_lock_offset);
diff --git a/drivers/clk/rockchip/gate-link.c b/drivers/clk/rockchip/gate-link.c
new file mode 100644
index 0000000000..710e77892a
--- /dev/null
+++ b/drivers/clk/rockchip/gate-link.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2024 Collabora Ltd.
+ * Author: Sebastian Reichel <sebastian.reichel@collabora.com>
+ */
+
+#include <common.h>
+
+#include "clk.h"
+
+static int rk_clk_gate_link_register(struct device *dev,
+				     struct rockchip_clk_provider *ctx,
+				     struct rockchip_clk_branch *clkbr)
+{
+	unsigned long flags = clkbr->flags | CLK_SET_RATE_PARENT;
+	struct clk *clk;
+
+	clk = clk_register_gate(dev, clkbr->name, clkbr->parent_names[0],
+				flags, ctx->reg_base + clkbr->gate_offset,
+				clkbr->gate_shift, clkbr->gate_flags,
+				&ctx->lock);
+
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	rockchip_clk_set_lookup(ctx, clk, clkbr->id);
+
+	return 0;
+}
+
+static int rk_clk_gate_link_probe(struct device *dev)
+{
+	struct rockchip_gate_link_platdata *pdata = dev->platform_data;
+	if (!pdata)
+		return dev_err_probe(dev, -ENODEV, "missing platform data");
+
+	return rk_clk_gate_link_register(dev, pdata->ctx, pdata->clkbr);
+}
+
+static struct driver rk_clk_gate_link_driver = {
+	.probe	= rk_clk_gate_link_probe,
+	.name	= "rockchip-gate-link-clk",
+};
+core_platform_driver(rk_clk_gate_link_driver);
-- 
2.39.1