clk: rockchip: add new clock-type for the ddrclk

Changing the rate of the DDR clock needs special care, as the DDR
is of course in use and will react badly if the rate changes under it.

Over time different approaches to handle that were used.

Past SoCs like the rk3288 and before would store some code in SRAM
while the rk3368 used a SCPI variant and let a coprocessor handle that.

New rockchip platforms like the rk3399 have a dcf controller to do ddr
frequency scaling, and support for this controller will be implemented
in the arm-trusted-firmware.

This new clock-type should over time handle all these methods for
handling DDR rate changes, but right now it will concentrate on the
SIP interface used to talk to ARM trusted firmware.

The SIP interface counterpart was merged from pull-request #684 [0]
into the upstream arm-trusted-firmware codebase.

[0] https://github.com/ARM-software/arm-trusted-firmware/pull/684

Signed-off-by: Lin Huang <hl@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

drivers/clk/rockchip/Makefile

@@ -8,6 +8,7 @@ obj-y	+= clk-pll.o
 obj-y	+= clk-cpu.o
 obj-y	+= clk-inverter.o
 obj-y	+= clk-mmc-phase.o
+obj-y	+= clk-ddr.o
 obj-$(CONFIG_RESET_CONTROLLER)	+= softrst.o
 
 obj-y	+= clk-rk3036.o

drivers/clk/rockchip/clk-ddr.c

@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2016 Rockchip Electronics Co. Ltd.
+ * Author: Lin Huang <hl@rock-chips.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <soc/rockchip/rockchip_sip.h>
+#include "clk.h"
+
+struct rockchip_ddrclk {
+	struct clk_hw	hw;
+	void __iomem	*reg_base;
+	int		mux_offset;
+	int		mux_shift;
+	int		mux_width;
+	int		div_shift;
+	int		div_width;
+	int		ddr_flag;
+	spinlock_t	*lock;
+};
+
+#define to_rockchip_ddrclk_hw(hw) container_of(hw, struct rockchip_ddrclk, hw)
+
+static int rockchip_ddrclk_sip_set_rate(struct clk_hw *hw, unsigned long drate,
+					unsigned long prate)
+{
+	struct rockchip_ddrclk *ddrclk = to_rockchip_ddrclk_hw(hw);
+	unsigned long flags;
+	struct arm_smccc_res res;
+
+	spin_lock_irqsave(ddrclk->lock, flags);
+	arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, drate, 0,
+		      ROCKCHIP_SIP_CONFIG_DRAM_SET_RATE,
+		      0, 0, 0, 0, &res);
+	spin_unlock_irqrestore(ddrclk->lock, flags);
+
+	return res.a0;
+}
+
+static unsigned long
+rockchip_ddrclk_sip_recalc_rate(struct clk_hw *hw,
+				unsigned long parent_rate)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, 0, 0,
+		      ROCKCHIP_SIP_CONFIG_DRAM_GET_RATE,
+		      0, 0, 0, 0, &res);
+
+	return res.a0;
+}
+
+static long rockchip_ddrclk_sip_round_rate(struct clk_hw *hw,
+					   unsigned long rate,
+					   unsigned long *prate)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, rate, 0,
+		      ROCKCHIP_SIP_CONFIG_DRAM_ROUND_RATE,
+		      0, 0, 0, 0, &res);
+
+	return res.a0;
+}
+
+static u8 rockchip_ddrclk_get_parent(struct clk_hw *hw)
+{
+	struct rockchip_ddrclk *ddrclk = to_rockchip_ddrclk_hw(hw);
+	int num_parents = clk_hw_get_num_parents(hw);
+	u32 val;
+
+	val = clk_readl(ddrclk->reg_base +
+			ddrclk->mux_offset) >> ddrclk->mux_shift;
+	val &= GENMASK(ddrclk->mux_width - 1, 0);
+
+	if (val >= num_parents)
+		return -EINVAL;
+
+	return val;
+}
+
+static const struct clk_ops rockchip_ddrclk_sip_ops = {
+	.recalc_rate = rockchip_ddrclk_sip_recalc_rate,
+	.set_rate = rockchip_ddrclk_sip_set_rate,
+	.round_rate = rockchip_ddrclk_sip_round_rate,
+	.get_parent = rockchip_ddrclk_get_parent,
+};
+
+struct clk *rockchip_clk_register_ddrclk(const char *name, int flags,
+					 const char *const *parent_names,
+					 u8 num_parents, int mux_offset,
+					 int mux_shift, int mux_width,
+					 int div_shift, int div_width,
+					 int ddr_flag, void __iomem *reg_base,
+					 spinlock_t *lock)
+{
+	struct rockchip_ddrclk *ddrclk;
+	struct clk_init_data init;
+	struct clk *clk;
+
+	ddrclk = kzalloc(sizeof(*ddrclk), GFP_KERNEL);
+	if (!ddrclk)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+
+	init.flags = flags;
+	init.flags |= CLK_SET_RATE_NO_REPARENT;
+
+	switch (ddr_flag) {
+	case ROCKCHIP_DDRCLK_SIP:
+		init.ops = &rockchip_ddrclk_sip_ops;
+		break;
+	default:
+		pr_err("%s: unsupported ddrclk type %d\n", __func__, ddr_flag);
+		kfree(ddrclk);
+		return ERR_PTR(-EINVAL);
+	}
+
+	ddrclk->reg_base = reg_base;
+	ddrclk->lock = lock;
+	ddrclk->hw.init = &init;
+	ddrclk->mux_offset = mux_offset;
+	ddrclk->mux_shift = mux_shift;
+	ddrclk->mux_width = mux_width;
+	ddrclk->div_shift = div_shift;
+	ddrclk->div_width = div_width;
+	ddrclk->ddr_flag = ddr_flag;
+
+	clk = clk_register(NULL, &ddrclk->hw);
+	if (IS_ERR(clk)) {
+		pr_err("%s: could not register ddrclk %s\n", __func__,	name);
+		kfree(ddrclk);
+		return NULL;
+	}
+
+	return clk;
+}

drivers/clk/rockchip/clk.c

@@ -484,6 +484,15 @@ void __init rockchip_clk_register_branches(
 				list->gate_offset, list->gate_shift,
 				list->gate_flags, flags, &ctx->lock);
 			break;
+		case branch_ddrclk:
+			clk = rockchip_clk_register_ddrclk(
+				list->name, list->flags,
+				list->parent_names, list->num_parents,
+				list->muxdiv_offset, list->mux_shift,
+				list->mux_width, list->div_shift,
+				list->div_width, list->div_flags,
+				ctx->reg_base, &ctx->lock);
+			break;
 		}
 
 		/* none of the cases above matched */

drivers/clk/rockchip/clk.h

@@ -281,6 +281,20 @@ struct clk *rockchip_clk_register_mmc(const char *name,
 				const char *const *parent_names, u8 num_parents,
 				void __iomem *reg, int shift);
 
+/*
+ * DDRCLK flags, including method of setting the rate
+ * ROCKCHIP_DDRCLK_SIP: use SIP call to bl31 to change ddrclk rate.
+ */
+#define ROCKCHIP_DDRCLK_SIP		BIT(0)
+
+struct clk *rockchip_clk_register_ddrclk(const char *name, int flags,
+					 const char *const *parent_names,
+					 u8 num_parents, int mux_offset,
+					 int mux_shift, int mux_width,
+					 int div_shift, int div_width,
+					 int ddr_flags, void __iomem *reg_base,
+					 spinlock_t *lock);
+
 #define ROCKCHIP_INVERTER_HIWORD_MASK	BIT(0)
 
 struct clk *rockchip_clk_register_inverter(const char *name,
@@ -299,6 +313,7 @@ enum rockchip_clk_branch_type {
 	branch_mmc,
 	branch_inverter,
 	branch_factor,
+	branch_ddrclk,
 };
 
 struct rockchip_clk_branch {
@@ -488,6 +503,24 @@ struct rockchip_clk_branch {
 		.child		= ch,				\
 	}
 
+#define COMPOSITE_DDRCLK(_id, cname, pnames, f, mo, ms, mw,	\
+			 ds, dw, df)				\
+	{							\
+		.id		= _id,				\
+		.branch_type	= branch_ddrclk,		\
+		.name		= cname,			\
+		.parent_names	= pnames,			\
+		.num_parents	= ARRAY_SIZE(pnames),		\
+		.flags		= f,				\
+		.muxdiv_offset  = mo,                           \
+		.mux_shift      = ms,                           \
+		.mux_width      = mw,                           \
+		.div_shift      = ds,                           \
+		.div_width      = dw,                           \
+		.div_flags	= df,				\
+		.gate_offset    = -1,                           \
+	}
+
 #define MUX(_id, cname, pnames, f, o, s, w, mf)			\
 	{							\
 		.id		= _id,				\