Hi Stephen,

On 22/07/2017 00:20, Stephen Boyd wrote:

On 07/13, Quentin Schulz wrote:

quoted

diff --git a/drivers/clk/at91/clk-audio-pll-pad.c b/drivers/clk/at91/clk-audio-pll-pad.c
new file mode 100644
index 000000000000..10dd6d625696
--- /dev/null
+++ b/drivers/clk/at91/clk-audio-pll-pad.c

@@ -0,0 +1,206 @@
+/*
+ *  Copyright (C) 2016 Atmel Corporation,
+ *                     Nicolas Ferre <nicolas.ferre@atmel.com>
+ *  Copyright (C) 2017 Free Electrons,
+ *		       Quentin Schulz <quentin.schulz@free-electrons.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.
+ *
+ */
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>

Used?

Not really, I need slab.h for kzalloc tough which was included by clkdev.

[...]

quoted

+static int clk_audio_pll_pad_set_rate(struct clk_hw *hw, unsigned long rate,
+				      unsigned long parent_rate)
+{
+	struct clk_audio_pad *apad_ck = to_clk_audio_pad(hw);
+	u8 tmp_div;
+
+	pr_debug("A PLL/PAD: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, parent_rate);
+
+	if (!rate)
+		return -EINVAL;

This happens?

I don't know, but it's better to do this quick check rather than being
exposed to a division by zero IMHO. Nothing in clk_ops states that the
rate given to set_rate is non-zero, so I made sure this can't happen.

quoted

+
+	tmp_div = parent_rate / rate;
+	if (tmp_div % 3 == 0) {
+		apad_ck->qdaudio = tmp_div / 3;
+		apad_ck->div = 3;
+	} else {
+		apad_ck->qdaudio = tmp_div / 2;
+		apad_ck->div = 2;
+	}[...]
+static void __init of_sama5d2_clk_audio_pll_pad_setup(struct device_node *np)
+{
+	struct clk_audio_pad *apad_ck;
+	struct clk_init_data init;

Best to initialize to { } just in case we add something later.

ACK.

quoted

+	struct regmap *regmap;
+	const char *parent_name;
+	const char *name = np->name;
+	int ret;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+
+	of_property_read_string(np, "clock-output-names", &name);
+
+	regmap = syscon_node_to_regmap(of_get_parent(np));
+	if (IS_ERR(regmap))
+		return;
+
+	apad_ck = kzalloc(sizeof(*apad_ck), GFP_KERNEL);
+	if (!apad_ck)
+		return;
+
+	init.name = name;
+	init.ops = &audio_pll_pad_ops;
+	init.parent_names = (parent_name ? &parent_name : NULL);

Use of_clk_parent_fill()?

[Deleting `parent_name = of_clk_get_parent_name(np, 0);`]
[Deleting `init.parent_names = (parent_name ? &parent_name : NULL);`]

+ const char *parent_names[1];
[...]
+ of_clk_parent_fill(np, parent_names, 1);
+ init.parent_names = parent_names;

Is it what you're asking?

quoted

+	init.num_parents = 1;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+		CLK_SET_RATE_PARENT;
+
+	apad_ck->hw.init = &init;
+	apad_ck->regmap = regmap;
+
+	ret = clk_hw_register(NULL, &apad_ck->hw);
+	if (ret)
+		kfree(apad_ck);
+	else
+		of_clk_add_hw_provider(np, of_clk_hw_simple_get, &apad_ck->hw);

Maybe we should make this register sequence a helper function.
Seems common.

I can put such an helper in an header if this is what you meant.

quoted

+}
+
+CLK_OF_DECLARE(of_sama5d2_clk_audio_pll_pad_setup,
+	       "atmel,sama5d2-clk-audio-pll-pad",
+	       of_sama5d2_clk_audio_pll_pad_setup);

We can't have a device driver for this?

Could you elaborate please?

quoted

diff --git a/drivers/clk/at91/clk-audio-pll-pmc.c b/drivers/clk/at91/clk-audio-pll-pmc.c
new file mode 100644
index 000000000000..7b0847ed7a4b
--- /dev/null
+++ b/drivers/clk/at91/clk-audio-pll-pmc.c

[...]

quoted

+static int clk_audio_pll_pmc_set_rate(struct clk_hw *hw, unsigned long rate,
+				      unsigned long parent_rate)
+{
+	struct clk_audio_pmc *apmc_ck = to_clk_audio_pmc(hw);
+
+	if (!rate)
+		return -EINVAL;
+
+	pr_debug("A PLL/PMC: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, parent_rate);
+
+	apmc_ck->qdpmc = parent_rate / rate - 1;

Hopefully rate isn't 1 or that goes undefined.

Thanks to operator precedence, the only check to do is rate != 0 (done
few lines above). Division has precedence over substraction.

[...]

quoted

+static void __init of_sama5d2_clk_audio_pll_pmc_setup(struct device_node *np)
+{
+	struct clk_audio_pmc *apmc_ck;
+	struct clk_init_data init;
+	struct regmap *regmap;
+	const char *parent_name;
+	const char *name = np->name;
+	int ret;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+
+	of_property_read_string(np, "clock-output-names", &name);
+
+	regmap = syscon_node_to_regmap(of_get_parent(np));
+	if (IS_ERR(regmap))
+		return;
+
+	apmc_ck = kzalloc(sizeof(*apmc_ck), GFP_KERNEL);
+	if (!apmc_ck)
+		return;
+
+	init.name = name;
+	init.ops = &audio_pll_pmc_ops;
+	init.parent_names = (parent_name ? &parent_name : NULL);

This feels repetitive.

quoted

+	init.num_parents = 1;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+		CLK_SET_RATE_PARENT;
+
+	apmc_ck->hw.init = &init;
+	apmc_ck->regmap = regmap;
+
+	ret = clk_hw_register(NULL, &apmc_ck->hw);
+	if (ret)
+		kfree(apmc_ck);
+	else
+		of_clk_add_hw_provider(np, of_clk_hw_simple_get, &apmc_ck->hw);
+}
+
+CLK_OF_DECLARE(of_sama5d2_clk_audio_pll_pmc_setup,
+	       "atmel,sama5d2-clk-audio-pll-pmc",
+	       of_sama5d2_clk_audio_pll_pmc_setup);

Very

Basically, both share almost the same code but have different formulae
for the rate.

quoted

diff --git a/drivers/clk/at91/clk-audio-pll.c b/drivers/clk/at91/clk-audio-pll.c
new file mode 100644
index 000000000000..efc2cb58da85
--- /dev/null
+++ b/drivers/clk/at91/clk-audio-pll.c

[...]

quoted

+static unsigned long clk_audio_pll_fout(unsigned long parent_rate,
+					unsigned long nd, unsigned long fracr)
+{
+	unsigned long long fr = (unsigned long long)parent_rate *
+						(unsigned long long)fracr;

We only need one cast here?

Indeed, I'll remove the casting of fracr.

[...]

quoted

+static long clk_audio_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *parent_rate)
+{
+	long best_rate = -EINVAL;
+	unsigned long fracr, nd;
+	int ret;
+
+	pr_debug("A PLL: %s, rate = %lu (parent_rate = %lu)\n", __func__, rate,
+		 *parent_rate);
+
+	if (rate < AUDIO_PLL_FOUT_MIN)
+		rate = AUDIO_PLL_FOUT_MIN;
+	else if (rate > AUDIO_PLL_FOUT_MAX)
+		rate = AUDIO_PLL_FOUT_MAX;

Use clamp. Also, did you want to use determine_rate callback and
clamp the requested rate range?

Didn't know this one, thanks!

I want determine_rate to return a valid rate for the pll so I clamp the
requested rate range in this one. In set_rate, I just tell the user that
any requested rate outside of the valid range is invalid. Does that
answer your question?

[...]

quoted

+static void __init of_sama5d2_clk_audio_pll_setup(struct device_node *np)
+{
+	struct clk_audio_frac *fck;
+	struct clk_init_data init;
+	struct regmap *regmap;
+	const char *parent_name;
+	const char *name = np->name;
+	int ret;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+
+	of_property_read_string(np, "clock-output-names", &name);

Any way to not rely on clock-output-names?

I guess we could use the name of the DT node (as it's done in the
variable initialization block above) and not override it by
clock-output-names?

quoted

+
+	regmap = syscon_node_to_regmap(of_get_parent(np));
+	if (IS_ERR(regmap))
+		return;
+
+	fck = kzalloc(sizeof(*fck), GFP_KERNEL);

This variable name looks like f*ck, perhaps name it something
else. frac?

Sure.

[...]

Thanks,
Quentin

-- 
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com