Message-ID: <9564d847-5374-f3f9-74ef-6e5eeed61c79@microchip.com>
Date:   Thu, 7 Oct 2021 16:13:37 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Kavyasree Kotagiri <kavyasree.kotagiri@...rochip.com>,
        <robh+dt@...nel.org>, <mturquette@...libre.com>, <sboyd@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <UNGLinuxDriver@...rochip.com>,
        <Eugen.Hristev@...rochip.com>, <Manohar.Puri@...rochip.com>
Subject: Re: [PATCH v7 3/3] clk: lan966x: Add lan966x SoC clock driver

On 30/09/2021 at 15:28, Kavyasree Kotagiri wrote:
> This adds Generic Clock Controller driver for lan966x SoC.
> 
> Lan966x clock controller contains 3 PLLs - cpu_clk, ddr_clk
> and sys_clk. It generates and supplies clock to various
> peripherals within SoC.
> Register settings required to provide GCK clocking to a
> peripheral is as below:
> GCK_SRC_SEL     = Select clock source.
> GCK_PRESCALER   = Set divider value.
> GCK_ENA         = 1 - Enable GCK clock.
> 
> Signed-off-by: Kavyasree Kotagiri <kavyasree.kotagiri@...rochip.com>
> Co-developed-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> Link: https://lore.kernel.org/r/20210930132815.15353-4-kavyasree.kotagiri@microchip.com
> ---
> v6 -> v7:
> - Added Kconfig and Makefile entires for lan966x clock driver.
> 
> v5 -> v6:
> - No changes.
> 
> v4 -> v5:
> - Returning proper error - PTR_ERR.
> - Removed unused variable "ret" in probe function.
> 
> v3 -> v4:
> - Used clk_parent_data instead of of_clk_get_parent_name().
> 
> v2 -> v3:
> - No changes.
> 
> v1 -> v2:
> - No changes.
> 
>   drivers/clk/Kconfig       |   7 ++
>   drivers/clk/Makefile      |   1 +
>   drivers/clk/clk-lan966x.c | 236 ++++++++++++++++++++++++++++++++++++++
>   3 files changed, 244 insertions(+)
>   create mode 100644 drivers/clk/clk-lan966x.c
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index c5b3dc97396a..1b992a554ff8 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -221,6 +221,13 @@ config COMMON_CLK_GEMINI
>   	  This driver supports the SoC clocks on the Cortina Systems Gemini
>   	  platform, also known as SL3516 or CS3516.
>   
> +config COMMON_CLK_LAN966X
> +	bool "Generic Clock Controller driver for LAN966X SoC"
> +	help
> +	  This driver provides support for Generic Clock Controller(GCK) on
> +	  LAN966X SoC. GCK generates and supplies clock to various peripherals
> +	  within the SoC.
> +
>   config COMMON_CLK_ASPEED
>   	bool "Clock driver for Aspeed BMC SoCs"
>   	depends on ARCH_ASPEED || COMPILE_TEST
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index e42312121e51..d8565ef01b34 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_ARCH_HIGHBANK)		+= clk-highbank.o
>   obj-$(CONFIG_CLK_HSDK)			+= clk-hsdk-pll.o
>   obj-$(CONFIG_COMMON_CLK_K210)		+= clk-k210.o
>   obj-$(CONFIG_LMK04832)			+= clk-lmk04832.o
> +obj-$(CONFIG_COMMON_CLK_LAN966X)	+= clk-lan966x.o
>   obj-$(CONFIG_COMMON_CLK_LOCHNAGAR)	+= clk-lochnagar.o
>   obj-$(CONFIG_COMMON_CLK_MAX77686)	+= clk-max77686.o
>   obj-$(CONFIG_COMMON_CLK_MAX9485)	+= clk-max9485.o
> diff --git a/drivers/clk/clk-lan966x.c b/drivers/clk/clk-lan966x.c
> new file mode 100644
> index 000000000000..0f24b95fd78f
> --- /dev/null
> +++ b/drivers/clk/clk-lan966x.c
> @@ -0,0 +1,236 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Microchip LAN966x SoC Clock driver.
> + *
> + * Copyright (C) 2021 Microchip Technology, Inc. and its subsidiaries
> + *
> + * Author: Kavyasree Kotagiri <kavyasree.kotagiri@...rochip.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk-provider.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#include <dt-bindings/clock/microchip,lan966x.h>
> +
> +#define GCK_ENA         BIT(0)
> +#define GCK_SRC_SEL     GENMASK(9, 8)
> +#define GCK_PRESCALER   GENMASK(23, 16)
> +
> +static const char *clk_names[N_CLOCKS] = {

What about using a dynamic table and then, in the code, use ARRAY_SIZE() 
macro in your loops? It might be more future proof if you add more 
peripherals or adapt this driver to another SoC.

As far as I see, your N_CLOCKS define can go away then.

> +	"qspi0", "qspi1", "qspi2", "sdmmc0",
> +	"pi", "mcan0", "mcan1", "flexcom0",
> +	"flexcom1", "flexcom2", "flexcom3",
> +	"flexcom4", "timer", "usb_refclk",
> +};
> +
> +struct lan966x_gck {
> +	struct clk_hw hw;
> +	void __iomem *reg;
> +};
> +#define to_lan966x_gck(hw) container_of(hw, struct lan966x_gck, hw)
> +
> +static const struct clk_parent_data lan966x_gck_pdata[] = {
> +	{ .fw_name = "cpu_clk", .name = "cpu_clk" },
> +	{ .fw_name = "ddr_clk", .name = "ddr_clk" },
> +	{ .fw_name = "sys_clk", .name = "sys_clk" },
> +};
> +
> +static struct clk_init_data init = {
> +	.parent_data = lan966x_gck_pdata,
> +	.num_parents = ARRAY_SIZE(lan966x_gck_pdata),
> +};
> +
> +static void __iomem *base;
> +
> +static int lan966x_gck_enable(struct clk_hw *hw)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 val = readl(gck->reg);
> +
> +	val |= GCK_ENA;
> +	writel(val, gck->reg);
> +
> +	return 0;
> +}
> +
> +static void lan966x_gck_disable(struct clk_hw *hw)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 val = readl(gck->reg);
> +
> +	val &= ~GCK_ENA;
> +	writel(val, gck->reg);
> +}
> +
> +static int lan966x_gck_set_rate(struct clk_hw *hw,
> +				unsigned long rate,
> +				unsigned long parent_rate)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 div, val = readl(gck->reg);
> +
> +	if (rate == 0 || parent_rate == 0)
> +		return -EINVAL;
> +
> +	/* Set Prescalar */
> +	div = parent_rate / rate;
> +	val &= ~GCK_PRESCALER;
> +	val |= FIELD_PREP(GCK_PRESCALER, (div - 1));
> +	writel(val, gck->reg);
> +
> +	return 0;
> +}
> +
> +static long lan966x_gck_round_rate(struct clk_hw *hw, unsigned long rate,
> +				   unsigned long *parent_rate)
> +{
> +	unsigned int div;
> +
> +	if (rate == 0 || *parent_rate == 0)
> +		return -EINVAL;
> +
> +	if (rate >= *parent_rate)
> +		return *parent_rate;
> +
> +	div = DIV_ROUND_CLOSEST(*parent_rate, rate);
> +
> +	return *parent_rate / div;
> +}
> +
> +static unsigned long lan966x_gck_recalc_rate(struct clk_hw *hw,
> +					     unsigned long parent_rate)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 div, val = readl(gck->reg);
> +
> +	div = FIELD_GET(GCK_PRESCALER, val);
> +
> +	return parent_rate / (div + 1);
> +}
> +
> +static int lan966x_gck_determine_rate(struct clk_hw *hw,
> +				      struct clk_rate_request *req)
> +{
> +	struct clk_hw *parent;
> +	int i;
> +
> +	for (i = 0; i < clk_hw_get_num_parents(hw); ++i) {
> +		parent = clk_hw_get_parent_by_index(hw, i);
> +		if (!parent)
> +			continue;
> +
> +		if (clk_hw_get_rate(parent) / req->rate < 254) {

I would use a well defined constant instead of this 254 number.

> +			req->best_parent_hw = parent;
> +			req->best_parent_rate = clk_hw_get_rate(parent);
> +
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static u8 lan966x_gck_get_parent(struct clk_hw *hw)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 val = readl(gck->reg);
> +
> +	return FIELD_GET(GCK_SRC_SEL, val);
> +}
> +
> +static int lan966x_gck_set_parent(struct clk_hw *hw, u8 index)
> +{
> +	struct lan966x_gck *gck = to_lan966x_gck(hw);
> +	u32 val = readl(gck->reg);
> +
> +	val &= ~GCK_SRC_SEL;
> +	val |= FIELD_PREP(GCK_SRC_SEL, index);
> +	writel(val, gck->reg);
> +
> +	return 0;
> +}
> +
> +static const struct clk_ops lan966x_gck_ops = {
> +	.enable         = lan966x_gck_enable,
> +	.disable        = lan966x_gck_disable,
> +	.set_rate       = lan966x_gck_set_rate,
> +	.round_rate     = lan966x_gck_round_rate,
> +	.recalc_rate    = lan966x_gck_recalc_rate,
> +	.determine_rate = lan966x_gck_determine_rate,
> +	.set_parent     = lan966x_gck_set_parent,
> +	.get_parent     = lan966x_gck_get_parent,
> +};
> +
> +static struct clk_hw *lan966x_gck_clk_register(struct device *dev, int i)
> +{
> +	struct lan966x_gck *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return ERR_PTR(-ENOMEM);
> +
> +	priv->reg = base + (i * 4);
> +	priv->hw.init = &init;
> +	ret = devm_clk_hw_register(dev, &priv->hw);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return &priv->hw;
> +};
> +
> +static int lan966x_clk_probe(struct platform_device *pdev)
> +{
> +	struct clk_hw_onecell_data *hw_data;
> +	struct device *dev = &pdev->dev;
> +	int i;
> +
> +	hw_data = devm_kzalloc(dev, sizeof(*hw_data), GFP_KERNEL);
> +	if (!hw_data)
> +		return -ENOMEM;
> +
> +	base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	init.ops = &lan966x_gck_ops;
> +
> +	hw_data->num = N_CLOCKS;
> +
> +	for (i = 0; i < N_CLOCKS; i++) {
> +		init.name = clk_names[i];
> +		hw_data->hws[i] = lan966x_gck_clk_register(dev, i);
> +		if (IS_ERR(hw_data->hws[i])) {
> +			dev_err(dev, "failed to register %s clock\n",
> +				init.name);
> +			return PTR_ERR(hw_data->hws[i]);
> +		}
> +	}
> +
> +	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, hw_data);
> +}
> +
> +static const struct of_device_id lan966x_clk_dt_ids[] = {
> +	{ .compatible = "microchip,lan966x-gck", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, lan966x_clk_dt_ids);
> +
> +static struct platform_driver lan966x_clk_driver = {
> +	.probe  = lan966x_clk_probe,
> +	.driver = {
> +		.name = "lan966x-clk",
> +		.of_match_table = lan966x_clk_dt_ids,
> +	},
> +};
> +builtin_platform_driver(lan966x_clk_driver);
> +
> +MODULE_AUTHOR("Kavyasree Kotagiri <kavyasree.kotagiri@...rochip.com>");
> +MODULE_DESCRIPTION("LAN966X clock driver");
> +MODULE_LICENSE("GPL v2");

The little remarks don't hold the driver approval, so you have my:

Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>

Best regards,
   Nicolas
-- 
Nicolas Ferre

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