Message-ID: <20170405013525.GJ18246@codeaurora.org>
Date:   Tue, 4 Apr 2017 18:35:25 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Vlad Zakharov <Vladislav.Zakharov@...opsys.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-snps-arc@...ts.infradead.org, devicetree@...r.kernel.org,
        Jose Abreu <Jose.Abreu@...opsys.com>,
        Michael Turquette <mturquette@...libre.com>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v2] clk/axs10x: introduce AXS10X pll driver

On 02/21, Vlad Zakharov wrote:
> diff --git a/Documentation/devicetree/bindings/clock/snps,pll-clock.txt b/Documentation/devicetree/bindings/clock/snps,pll-clock.txt
> new file mode 100644
> index 0000000..5706246
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/snps,pll-clock.txt
> @@ -0,0 +1,28 @@
> +Binding for the AXS10X Generic PLL clock
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible: should be "snps,axs10x-<name>-pll-clock"
> +  "snps,axs10x-arc-pll-clock"
> +  "snps,axs10x-pgu-pll-clock"
> +- reg: should always contain 2 pairs address - length: first for PLL config
> +registers and second for corresponding LOCK CGU register.
> +- clocks: shall be the input parent clock phandle for the PLL.
> +- #clock-cells: from common clock binding; Should always be set to 0.
> +
> +Example:
> +	input-clk: input-clk {
> +		clock-frequency = <33333333>;
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +	};
> +
> +	core-clk: core-clk@80 {
> +		compatible = "snps,axs10x-arc-pll-clock";
> +		reg = <0x80 0x10 0x100 0x10>;

Can you add the braces around register pairs in the example?
Makes it clearer with a quick glance.

> +		#clock-cells = <0>;
> +		clocks = <&input-clk>;
> +	};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3960e7f..5805833 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11910,6 +11910,12 @@ F:	arch/arc/plat-axs10x
>  F:	arch/arc/boot/dts/ax*
>  F:	Documentation/devicetree/bindings/arc/axs10*
>  
> +SYNOPSYS ARC SDP clock driver

This also includes the existing driver there. Jose can ack this?

> +M:	Vlad Zakharov <vzakhar@...opsys.com>
> +S:	Supported
> +F:	drivers/clk/axs10x/*
> +F:	Documentation/devicetree/bindings/clock/snps,pll-clock.txt
> +
>  SYSTEM CONFIGURATION (SYSCON)
>  M:	Lee Jones <lee.jones@...aro.org>
>  M:	Arnd Bergmann <arnd@...db.de>
> diff --git a/drivers/clk/axs10x/Makefile b/drivers/clk/axs10x/Makefile
> index 01996b8..d747dea 100644
> --- a/drivers/clk/axs10x/Makefile
> +++ b/drivers/clk/axs10x/Makefile
> @@ -1 +1,2 @@
>  obj-y += i2s_pll_clock.o
> +obj-y += pll_clock.o
> diff --git a/drivers/clk/axs10x/pll_clock.c b/drivers/clk/axs10x/pll_clock.c
> new file mode 100644
> index 0000000..784a0a2
> --- /dev/null
> +++ b/drivers/clk/axs10x/pll_clock.c
> @@ -0,0 +1,384 @@
> +/*
> + * Synopsys AXS10X SDP Generic PLL clock driver
> + *
> + * Copyright (C) 2017 Synopsys
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/clk-provider.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/device.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +
> +/* PLL registers addresses */
> +#define PLL_REG_IDIV	0x0
> +#define PLL_REG_FBDIV	0x4
> +#define PLL_REG_ODIV	0x8
> +
> +/*
> + * Bit fields of the PLL IDIV/FBDIV/ODIV registers:
> + *  ________________________________________________________________________
> + * |31                15|    14    |   13   |  12  |11         6|5         0|
> + * |-------RESRVED------|-NOUPDATE-|-BYPASS-|-EDGE-|--HIGHTIME--|--LOWTIME--|
> + * |____________________|__________|________|______|____________|___________|
> + *
> + * Following macros detirmine the way of access to these registers

s/detirmine/determine/

> + * They should be set up only using the macros.
> + * reg should be and uint32_t variable.

s/and/an/?

> + */
> +
> +#define PLL_REG_GET_LOW(reg)			\
> +	(((reg) & (0x3F << 0)) >> 0)
> +#define PLL_REG_GET_HIGH(reg)			\
> +	(((reg) & (0x3F << 6)) >> 6)
> +#define PLL_REG_GET_EDGE(reg)			\
> +	(((reg) & (BIT(12))) ? 1 : 0)
> +#define PLL_REG_GET_BYPASS(reg)			\
> +	(((reg) & (BIT(13))) ? 1 : 0)
> +#define PLL_REG_GET_NOUPD(reg)			\
> +	(((reg) & (BIT(14))) ? 1 : 0)
> +#define PLL_REG_GET_PAD(reg)			\
> +	(((reg) & (0x1FFFF << 15)) >> 15)
> +
> +#define PLL_REG_SET_LOW(reg, value)		\
> +	{ reg |= (((value) & 0x3F) << 0); }
> +#define PLL_REG_SET_HIGH(reg, value)	\
> +	{ reg |= (((value) & 0x3F) << 6); }
> +#define PLL_REG_SET_EDGE(reg, value)	\
> +	{ reg |= (((value) & 0x01) << 12); }
> +#define PLL_REG_SET_BYPASS(reg, value)	\
> +	{ reg |= (((value) & 0x01) << 13); }
> +#define PLL_REG_SET_NOUPD(reg, value)	\
> +	{ reg |= (((value) & 0x01) << 14); }
> +#define PLL_REG_SET_PAD(reg, value)		\
> +	{ reg |= (((value) & 0x1FFFF) << 15); }
> +
> +#define PLL_LOCK	0x1
> +#define PLL_MAX_LOCK_TIME 100 /* 100 us */
> +
> +struct pll_cfg {
> +	u32 rate;
> +	u32 idiv;
> +	u32 fbdiv;
> +	u32 odiv;
> +};
> +
> +struct pll_of_table {
> +	unsigned long prate;
> +	struct pll_cfg *pll_cfg_table;

const?

> +};
> +
> +struct pll_of_data {
> +	struct pll_of_table *pll_table;
> +};

Why the structure for another structure pointer? Just use
pll_of_table for now?

> +
> +static struct pll_of_data pgu_pll_data = {

const?

> +	.pll_table = (struct pll_of_table []){
> +		{
> +			.prate = 27000000,

Can this be another clk in the framework instead of hardcoding
the parent rate?

> +			.pll_cfg_table = (struct pll_cfg []){
> +				{ 25200000, 1, 84, 90 },
> +				{ 50000000, 1, 100, 54 },
> +				{ 74250000, 1, 44, 16 },
> +				{ },
> +			},
> +		},
> +		/* Used as list limiter */
> +		{ },

There's only ever one, so I'm confused why we're making a list.

> +	},
> +};
> +
> +static struct pll_of_data arc_pll_data = {

const?

> +	.pll_table = (struct pll_of_table []){
> +		{
> +			.prate = 33333333,
> +			.pll_cfg_table = (struct pll_cfg []){
> +				{ 33333333,  1, 1,  1 },
> +				{ 50000000,  1, 30, 20 },
> +				{ 75000000,  2, 45, 10 },
> +				{ 90000000,  2, 54, 10 },
> +				{ 100000000, 1, 30, 10 },
> +				{ 125000000, 2, 45, 6 },
> +				{ },
> +			},
> +		},
> +		/* Used as list limiter */
> +		{ },
> +	},
> +};
> +
> +struct pll_clk {
> +	void __iomem *base;
> +	void __iomem *lock;
> +	const struct pll_of_data *pll_data;
> +	struct clk_hw hw;
> +	struct device *dev;
> +};
> +
> +static inline void pll_write(struct pll_clk *clk, unsigned int reg,
> +		unsigned int val)
> +{
> +	iowrite32(val, clk->base + reg);
> +}
> +
> +static inline u32 pll_read(struct pll_clk *clk,
> +		unsigned int reg)

reg can go on the same line as clk?

> +{
> +	return ioread32(clk->base + reg);
> +}
> +
> +static inline struct pll_clk *to_pll_clk(struct clk_hw *hw)
> +{
> +	return container_of(hw, struct pll_clk, hw);
> +}
> +
> +static inline u32 div_get_value(unsigned int reg)
> +{
> +	if (PLL_REG_GET_BYPASS(reg))
> +		return 1;
> +
> +	return (PLL_REG_GET_HIGH(reg) + PLL_REG_GET_LOW(reg));

Useless parenthesis.

> +}
> +
> +static inline u32 encode_div(unsigned int id, int upd)
> +{
> +	uint32_t div = 0;
> +
> +	PLL_REG_SET_LOW(div, (id%2 == 0) ? id >> 1 : (id >> 1) + 1);
> +	PLL_REG_SET_HIGH(div, id >> 1);
> +	PLL_REG_SET_EDGE(div, id%2);
> +	PLL_REG_SET_BYPASS(div, id == 1 ? 1 : 0);
> +	PLL_REG_SET_NOUPD(div, !upd);
> +
> +	return div;
> +}
> +
> +static const struct pll_cfg *pll_get_cfg(unsigned long prate,
> +		const struct pll_of_table *pll_table)
> +{
> +	int i;
> +
> +	for (i = 0; pll_table[i].prate != 0; i++)
> +		if (pll_table[i].prate == prate)
> +			return pll_table[i].pll_cfg_table;
> +
> +	return NULL;
> +}
> +
> +static unsigned long pll_recalc_rate(struct clk_hw *hw,
> +			unsigned long parent_rate)
> +{
> +	u64 rate;
> +	u32 idiv, fbdiv, odiv;
> +	struct pll_clk *clk = to_pll_clk(hw);
> +
> +	idiv = div_get_value(pll_read(clk, PLL_REG_IDIV));
> +	fbdiv = div_get_value(pll_read(clk, PLL_REG_FBDIV));
> +	odiv = div_get_value(pll_read(clk, PLL_REG_ODIV));
> +
> +	rate = (u64)parent_rate * fbdiv;
> +	do_div(rate, idiv * odiv);
> +
> +	return (unsigned long)rate;

Useless cast?

> +}
> +
> +static long pll_round_rate(struct clk_hw *hw, unsigned long rate,
> +			unsigned long *prate)
> +{
> +	int i;
> +	long best_rate;
> +	struct pll_clk *clk = to_pll_clk(hw);
> +	const struct pll_cfg *pll_cfg = pll_get_cfg(*prate,
> +			clk->pll_data->pll_table);
> +
> +	if (!pll_cfg) {
> +		dev_err(clk->dev, "invalid parent rate=%ld\n", *prate);
> +		return -EINVAL;
> +	}
> +
> +	if (pll_cfg[0].rate == 0)
> +		return -EINVAL;
> +
> +	best_rate = pll_cfg[0].rate;
> +
> +	for (i = 1; pll_cfg[i].rate != 0; i++) {
> +		if (abs(rate - pll_cfg[i].rate) < abs(rate - best_rate))
> +			best_rate = pll_cfg[i].rate;
> +	}
> +
> +	return best_rate;
> +}
> +
> +static int pll_set_rate(struct clk_hw *hw, unsigned long rate,
> +			unsigned long parent_rate)
> +{
> +	int i;
> +	struct pll_clk *clk = to_pll_clk(hw);
> +	const struct pll_cfg *pll_cfg = pll_get_cfg(parent_rate,
> +			clk->pll_data->pll_table);
> +
> +	if (!pll_cfg) {
> +		dev_err(clk->dev, "invalid parent rate=%ld\n", parent_rate);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; pll_cfg[i].rate != 0; i++) {
> +		if (pll_cfg[i].rate == rate) {
> +			pll_write(clk, PLL_REG_IDIV,
> +					encode_div(pll_cfg[i].idiv, 0));
> +			pll_write(clk, PLL_REG_FBDIV,
> +					encode_div(pll_cfg[i].fbdiv, 0));
> +			pll_write(clk, PLL_REG_ODIV,
> +					encode_div(pll_cfg[i].odiv, 1));
> +
> +			/*
> +			 * Wait until CGU relocks.
> +			 * If after timeout CGU is unlocked yet return error
> +			 */
> +			udelay(PLL_MAX_LOCK_TIME);
> +			if (ioread32(clk->lock) & PLL_LOCK)
> +				return 0;
> +			else
> +				return -ETIMEDOUT;

Can just be a return without the else part.

> +		}
> +	}
> +
> +	dev_err(clk->dev, "invalid rate=%ld, parent_rate=%ld\n", rate,
> +			parent_rate);
> +	return -EINVAL;
> +}
> +
> +static const struct clk_ops pll_ops = {
> +	.recalc_rate = pll_recalc_rate,
> +	.round_rate = pll_round_rate,
> +	.set_rate = pll_set_rate,
> +};
> +
> +static int pll_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const char *parent_name;
> +	struct clk *clk;
> +	struct pll_clk *pll_clk;
> +	struct resource *mem;
> +	struct clk_init_data init = { };
> +
> +	pll_clk = devm_kzalloc(dev, sizeof(*pll_clk), GFP_KERNEL);
> +	if (!pll_clk)
> +		return -ENOMEM;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	pll_clk->base = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(pll_clk->base))
> +		return PTR_ERR(pll_clk->base);
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	pll_clk->lock = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(pll_clk->lock))
> +		return PTR_ERR(pll_clk->base);
> +
> +	init.name = dev->of_node->name;
> +	init.ops = &pll_ops;
> +	parent_name = of_clk_get_parent_name(dev->of_node, 0);
> +	init.parent_names = &parent_name;
> +	init.num_parents = 1;
> +	pll_clk->hw.init = &init;
> +	pll_clk->dev = dev;
> +	pll_clk->pll_data = of_device_get_match_data(dev);
> +
> +	if (!pll_clk->pll_data) {
> +		dev_err(dev, "No OF match data provided\n");
> +			return -EINVAL;
> +	}
> +
> +	clk = devm_clk_register(dev, &pll_clk->hw);
> +	if (IS_ERR(clk)) {
> +		dev_err(dev, "failed to register %s clock (%ld)\n",
> +				init.name, PTR_ERR(clk));
> +		return PTR_ERR(clk);
> +	}
> +
> +	return of_clk_add_provider(dev->of_node, of_clk_src_simple_get, clk);
> +}
> +
> +static int pll_clk_remove(struct platform_device *pdev)
> +{
> +	of_clk_del_provider(pdev->dev.of_node);
> +	return 0;
> +}
> +
> +static void __init of_pll_clk_setup(struct device_node *node)
> +{
> +	const char *parent_name;
> +	struct clk *clk;
> +	struct pll_clk *pll_clk;
> +	struct clk_init_data init = { };
> +
> +	pll_clk = kzalloc(sizeof(*pll_clk), GFP_KERNEL);
> +	if (!pll_clk)
> +		return;
> +
> +	pll_clk->base = of_iomap(node, 0);
> +	if (!pll_clk->base) {
> +		pr_err("failed to map pll div registers\n");
> +		iounmap(pll_clk->base);
> +		return;
> +	}
> +
> +	pll_clk->lock = of_iomap(node, 1);
> +	if (!pll_clk->lock) {
> +		pr_err("failed to map pll lock register\n");
> +		iounmap(pll_clk->lock);
> +		return;
> +	}
> +
> +	init.name = node->name;
> +	init.ops = &pll_ops;
> +	parent_name = of_clk_get_parent_name(node, 0);
> +	init.parent_names = &parent_name;
> +	init.num_parents = parent_name ? 1 : 0;
> +	pll_clk->hw.init = &init;
> +	pll_clk->pll_data = &arc_pll_data;
> +
> +	clk = clk_register(NULL, &pll_clk->hw);
> +	if (IS_ERR(clk)) {
> +		pr_err("failed to register %s clock (%ld)\n",
> +				node->name, PTR_ERR(clk));
> +		kfree(pll_clk);
> +		return;
> +	}
> +
> +	of_clk_add_provider(node, of_clk_src_simple_get, clk);

Can you please use the clk_hw based provider and clk registration
functions?

> +}
> +
> +CLK_OF_DECLARE(axs10x_pll_clock, "snps,axs10x-arc-pll-clock", of_pll_clk_setup);

Does this need to be CLK_OF_DECLARE_DRIVER? I mean does the
driver need to probe and also have this of declare happen? Is the
PLL special and needs to be used for the timers?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Powered by blists - more mailing lists