Re: [PATCH v9 07/12] clk: meson: add vclk driver

From: neil . armstrong
Date: Mon Feb 05 2024 - 12:27:20 EST

On 27/11/2023 17:24, Jerome Brunet wrote:

On Mon 27 Nov 2023 at 17:14, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:

On 24/11/2023 15:41, Jerome Brunet wrote:
On Fri 24 Nov 2023 at 09:41, Neil Armstrong <neil.armstrong@xxxxxxxxxx>
wrote:

The VCLK and VCLK_DIV clocks have supplementary bits.

The VCLK has a "SOFT RESET" bit to toggle after the whole
VCLK sub-tree rate has been set, this is implemented in
the gate enable callback.

The VCLK_DIV clocks as enable and reset bits used to disable
and reset the divider, associated with CLK_SET_RATE_GATE it ensures
the rate is set while the divider is disabled and in reset mode.

The VCLK_DIV enable bit isn't implemented as a gate since it's part
of the divider logic and vendor does this exact sequence to ensure
the divider is correctly set.

Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
---
drivers/clk/meson/Kconfig | 5 ++
drivers/clk/meson/Makefile | 1 +
drivers/clk/meson/vclk.c | 141 +++++++++++++++++++++++++++++++++++++++++++++
drivers/clk/meson/vclk.h | 51 ++++++++++++++++
4 files changed, 198 insertions(+)

diff --git a/drivers/clk/meson/Kconfig b/drivers/clk/meson/Kconfig
index 29ffd14d267b..59a40a49f8e1 100644
--- a/drivers/clk/meson/Kconfig
+++ b/drivers/clk/meson/Kconfig
@@ -30,6 +30,10 @@ config COMMON_CLK_MESON_VID_PLL_DIV
tristate
select COMMON_CLK_MESON_REGMAP
+config COMMON_CLK_MESON_VCLK
+ tristate
+ select COMMON_CLK_MESON_REGMAP
+
config COMMON_CLK_MESON_CLKC_UTILS
tristate
@@ -140,6 +144,7 @@ config COMMON_CLK_G12A
select COMMON_CLK_MESON_EE_CLKC
select COMMON_CLK_MESON_CPU_DYNDIV
select COMMON_CLK_MESON_VID_PLL_DIV
+ select COMMON_CLK_MESON_VCLK
This particular line belong in the next patch

select MFD_SYSCON
help
Support for the clock controller on Amlogic S905D2, S905X2 and S905Y2
diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
index 9ee4b954c896..9ba43fe7a07a 100644
--- a/drivers/clk/meson/Makefile
+++ b/drivers/clk/meson/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_COMMON_CLK_MESON_PLL) += clk-pll.o
obj-$(CONFIG_COMMON_CLK_MESON_REGMAP) += clk-regmap.o
obj-$(CONFIG_COMMON_CLK_MESON_SCLK_DIV) += sclk-div.o
obj-$(CONFIG_COMMON_CLK_MESON_VID_PLL_DIV) += vid-pll-div.o
+obj-$(CONFIG_COMMON_CLK_MESON_VCLK) += vclk.o
# Amlogic Clock controllers
diff --git a/drivers/clk/meson/vclk.c b/drivers/clk/meson/vclk.c
new file mode 100644
index 000000000000..47f08a52b49f
--- /dev/null
+++ b/drivers/clk/meson/vclk.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 Neil Armstrong <neil.armstrong@xxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include "vclk.h"
+
+/* The VCLK gate has a supplementary reset bit to pulse after ungating */
+
+static inline struct clk_regmap_vclk_data *
+clk_get_regmap_vclk_data(struct clk_regmap *clk)
+{
+ return (struct clk_regmap_vclk_data *)clk->data;
+}
+
+static int clk_regmap_vclk_enable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
+
+ meson_parm_write(clk->map, &vclk->enable, 1);
+
+ /* Do a reset pulse */
+ meson_parm_write(clk->map, &vclk->reset, 1);
+ meson_parm_write(clk->map, &vclk->reset, 0);
+
+ return 0;
+}
+
+static void clk_regmap_vclk_disable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
+
+ meson_parm_write(clk->map, &vclk->enable, 0);
+}
+
+static int clk_regmap_vclk_is_enabled(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
+
+ return meson_parm_read(clk->map, &vclk->enable);
+}
+
+const struct clk_ops clk_regmap_vclk_ops = {
+ .enable = clk_regmap_vclk_enable,
+ .disable = clk_regmap_vclk_disable,
+ .is_enabled = clk_regmap_vclk_is_enabled,
+};
+EXPORT_SYMBOL_GPL(clk_regmap_vclk_ops);
s/clk_regmap_vclk/meson_vclk at least for what is exported, ideally most
all the code.
I get clk_regmap_ comes from code copied from clk_regmap.c.
The reason the this part is different (and not using parm) if that when
I converted amlogic to regmap, I hope we could make this generic,
possibly converging between aml and qcom (which was the only other
platform using regmap for clock at the time). This is why clk_regmap.c
is a bit different from the other driver.
For the aml specific drivers, best to look at the mpll or cpu-dyndiv one.

+
+/* The VCLK Divider has supplementary reset & enable bits */
+
+static inline struct clk_regmap_vclk_div_data *
+clk_get_regmap_vclk_div_data(struct clk_regmap *clk)
+{
+ return (struct clk_regmap_vclk_div_data *)clk->data;
+}
+
+static unsigned long clk_regmap_vclk_div_recalc_rate(struct clk_hw *hw,
+ unsigned long prate)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+
+ return divider_recalc_rate(hw, prate, meson_parm_read(clk->map, &vclk->div),
+ vclk->table, vclk->flags, vclk->div.width);
+}
+
+static int clk_regmap_vclk_div_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+
+ return divider_determine_rate(hw, req, vclk->table, vclk->div.width,
+ vclk->flags);
+}
+
+static int clk_regmap_vclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+ int ret;
+
+ ret = divider_get_val(rate, parent_rate, vclk->table, vclk->div.width,
+ vclk->flags);
+ if (ret < 0)
+ return ret;
+
+ meson_parm_write(clk->map, &vclk->div, ret);
+
+ return 0;
+};
+
+static int clk_regmap_vclk_div_enable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+
+ /* Unreset the divider when ungating */
+ meson_parm_write(clk->map, &vclk->reset, 0);
+ meson_parm_write(clk->map, &vclk->enable, 1);
+
+ return 0;
+}
+
+static void clk_regmap_vclk_div_disable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+
+ /* Reset the divider when gating */
+ meson_parm_write(clk->map, &vclk->enable, 0);
+ meson_parm_write(clk->map, &vclk->reset, 1);
+}
+
+static int clk_regmap_vclk_div_is_enabled(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
+
+ return meson_parm_read(clk->map, &vclk->enable);
+}
+
+const struct clk_ops clk_regmap_vclk_div_ops = {
+ .recalc_rate = clk_regmap_vclk_div_recalc_rate,
+ .determine_rate = clk_regmap_vclk_div_determine_rate,
+ .set_rate = clk_regmap_vclk_div_set_rate,
+ .enable = clk_regmap_vclk_div_enable,
+ .disable = clk_regmap_vclk_div_disable,
+ .is_enabled = clk_regmap_vclk_div_is_enabled,
+};
+EXPORT_SYMBOL_GPL(clk_regmap_vclk_div_ops);
+
+MODULE_DESCRIPTION("Amlogic vclk clock driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@xxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/clk/meson/vclk.h b/drivers/clk/meson/vclk.h
new file mode 100644
index 000000000000..4f25d7ad2717
--- /dev/null
+++ b/drivers/clk/meson/vclk.h

Is vclk.c/h ok ? clk-vclk doesn't look pretty, but I can switch to it to
keep files organized.

I don't have a strong opinion about it.
I would have suggested vclk-div.c/h - like sclk ... but you do have gate
ops in there, so ... :/

This made me realize that one does not really go without the other.
It is more a coherent block, isn't it ?
Would it make more sense to have these 2 merged in a single clk_ops ?

No those a 2 separate blocks, one is for VCLK clock input and the other is for the DIV
block, and the reset isn't used in the same way so I can't merge them.


It's bit late to point this out, sorry about that.

I let you decide whether to merge the ops or not and which name to pick.

If you keep them separated, meson_vclk_gate_ops instead of just
meson_vclk_ops, to make things clear.

Ack



Neil

@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023 Neil Armstrong <neil.armstrong@xxxxxxxxxx>
+ */
+
+#ifndef __VCLK_H
+#define __VCLK_H
This is too generic.
Please add the MESON prefix like the other clock driver please.

+
+#include "clk-regmap.h"
+#include "parm.h"
+
+/**
+ * struct clk_regmap_vclk_data - vclk regmap backed specific data
+ *
+ * @enable: vclk enable field
+ * @reset: vclk reset field
+ * @flags: hardware-specific flags
+ *
+ * Flags:
+ * Same as clk_gate except CLK_GATE_HIWORD_MASK which is ignored
+ */
+struct clk_regmap_vclk_data {
+ struct parm enable;
+ struct parm reset;
+ u8 flags;
+};
+
+extern const struct clk_ops clk_regmap_vclk_ops;
+
+/**
+ * struct clk_regmap_vclk_div_data - vclk_div regmap back specific data
+ *
+ * @div: divider field
+ * @enable: vclk divider enable field
+ * @reset: vclk divider reset field
+ * @table: array of value/divider pairs, last entry should have div = 0
+ *
+ * Flags:
+ * Same as clk_divider except CLK_DIVIDER_HIWORD_MASK which is ignored
+ */
+struct clk_regmap_vclk_div_data {
+ struct parm div;
+ struct parm enable;
+ struct parm reset;
+ const struct clk_div_table *table;
+ u8 flags;
+};
+
+extern const struct clk_ops clk_regmap_vclk_div_ops;
+
+#endif /* __VCLK_H */