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Date: Wed, 17 Oct 2018 12:55:52 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Abel Vesa <abel.vesa@....com>,
Andrey Smirnov <andrew.smirnov@...il.com>,
Anson Huang <anson.huang@....com>,
Dong Aisheng <aisheng.dong@....com>,
Fabio Estevam <fabio.estevam@....com>,
Lucas Stach <l.stach@...gutronix.de>,
Rob Herring <robh@...nel.org>,
Sascha Hauer <kernel@...gutronix.de>
Cc: linux-imx@....com, Abel Vesa <abelvesa@...ux.com>,
Abel Vesa <abel.vesa@....com>, Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Michael Turquette <mturquette@...libre.com>,
open list <linux-kernel@...r.kernel.org>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@...ts.infradead.org>,
"open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v9 3/5] clk: imx: add SCCG PLL type
Quoting Abel Vesa (2018-09-24 03:39:55)
> diff --git a/drivers/clk/imx/clk-sccg-pll.c b/drivers/clk/imx/clk-sccg-pll.c
> new file mode 100644
> index 0000000..a9837fa
> --- /dev/null
> +++ b/drivers/clk/imx/clk-sccg-pll.c
> @@ -0,0 +1,237 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Copyright 2018 NXP.
> + */
> +
> +#include <linux/clk.h>
Is this include used? Otherwise should see clk-provider.h included here.
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/bitfield.h>
> +
> +#include "clk.h"
> +
> +/* PLL CFGs */
> +#define PLL_CFG0 0x0
> +#define PLL_CFG1 0x4
> +#define PLL_CFG2 0x8
> +
> +#define PLL_DIVF1_MASK GENMASK(18, 13)
> +#define PLL_DIVF2_MASK GENMASK(12, 7)
> +#define PLL_DIVR1_MASK GENMASK(27, 25)
> +#define PLL_DIVR2_MASK GENMASK(24, 19)
> +#define PLL_REF_MASK GENMASK(2, 0)
> +
> +#define PLL_LOCK_MASK BIT(31)
> +#define PLL_PD_MASK BIT(7)
> +
> +#define OSC_25M 25000000
> +#define OSC_27M 27000000
> +
> +#define PLL_SCCG_LOCK_TIMEOUT 70
> +
> +struct clk_sccg_pll {
> + struct clk_hw hw;
> + void __iomem *base;
> +};
> +
> +#define to_clk_sccg_pll(_hw) container_of(_hw, struct clk_sccg_pll, hw)
> +
> +static int clk_pll_wait_lock(struct clk_sccg_pll *pll)
> +{
> + u32 val;
> +
> + return readl_poll_timeout(pll->base, val, val & PLL_LOCK_MASK, 0,
> + PLL_SCCG_LOCK_TIMEOUT);
> +}
> +
> +static int clk_pll1_is_prepared(struct clk_hw *hw)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val;
> +
> + val = readl_relaxed(pll->base + PLL_CFG0);
> + return (val & PLL_PD_MASK) ? 0 : 1;
> +}
> +
> +static unsigned long clk_pll1_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val, divf;
> +
> + val = readl_relaxed(pll->base + PLL_CFG2);
> + divf = FIELD_GET(PLL_DIVF1_MASK, val);
> +
> + return parent_rate * 2 * (divf + 1);
> +}
> +
> +static long clk_pll1_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate)
> +{
> + unsigned long parent_rate = *prate;
> + u32 div;
> +
> + div = rate / (parent_rate * 2);
Can parent_rate be 0?
> +
> + return parent_rate * div * 2;
> +}
> +
> +static int clk_pll1_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val;
> + u32 divf;
> +
> + divf = rate / (parent_rate * 2);
Can parent_rate be 0?
> +
> + val = readl_relaxed(pll->base + PLL_CFG2);
> + val &= ~PLL_DIVF1_MASK;
> + val |= FIELD_PREP(PLL_DIVF1_MASK, divf - 1);
> + writel_relaxed(val, pll->base + PLL_CFG2);
> +
> + return clk_pll_wait_lock(pll);
> +}
> +
> +static int clk_pll1_prepare(struct clk_hw *hw)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val;
> +
> + val = readl_relaxed(pll->base + PLL_CFG0);
> + val &= ~PLL_PD_MASK;
> + writel_relaxed(val, pll->base + PLL_CFG0);
> +
> + return clk_pll_wait_lock(pll);
> +}
> +
> +static void clk_pll1_unprepare(struct clk_hw *hw)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val;
> +
> + val = readl_relaxed(pll->base + PLL_CFG0);
> + val |= PLL_PD_MASK;
> + writel_relaxed(val, pll->base + PLL_CFG0);
> +
> +}
> +
> +static unsigned long clk_pll2_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> + u32 val, ref, divr1, divf1, divr2, divf2;
> + u64 temp64;
> +
> + val = readl_relaxed(pll->base + PLL_CFG0);
> + switch (FIELD_GET(PLL_REF_MASK, val)) {
> + case 0:
> + ref = OSC_25M;
> + break;
> + case 1:
> + ref = OSC_27M;
> + break;
> + default:
> + ref = OSC_25M;
Does this information not come through 'parent_rate'?
> + break;
> + }
> +
> + val = readl_relaxed(pll->base + PLL_CFG2);
> + divr1 = FIELD_GET(PLL_DIVR1_MASK, val);
> + divr2 = FIELD_GET(PLL_DIVR2_MASK, val);
> + divf1 = FIELD_GET(PLL_DIVF1_MASK, val);
> + divf2 = FIELD_GET(PLL_DIVF2_MASK, val);
> +
> + temp64 = ref * 2;
> + temp64 *= (divf1 + 1) * (divf2 + 1);
> +
> + do_div(temp64, (divr1 + 1) * (divr2 + 1));
Nitpicks: A comment with the equation may be helpful to newcomers.
> +
> + return (unsigned long)temp64;
Drop useless cast please.
> +}
> +
> +static long clk_pll2_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate)
> +{
> + u32 div;
> + unsigned long parent_rate = *prate;
> +
> + div = rate / (parent_rate);
> +
> + return parent_rate * div;
> +}
> +
> +static int clk_pll2_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + u32 val;
> + u32 divf;
> + struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +
> + divf = rate / (parent_rate);
Drop useless parenthesis please.
> +
> + val = readl_relaxed(pll->base + PLL_CFG2);
> + val &= ~PLL_DIVF2_MASK;
> + val |= FIELD_PREP(PLL_DIVF2_MASK, divf - 1);
> + writel_relaxed(val, pll->base + PLL_CFG2);
> +
> + return clk_pll_wait_lock(pll);
> +}
> +
> +static const struct clk_ops clk_sccg_pll1_ops = {
> + .is_prepared = clk_pll1_is_prepared,
> + .recalc_rate = clk_pll1_recalc_rate,
> + .round_rate = clk_pll1_round_rate,
> + .set_rate = clk_pll1_set_rate,
> +};
> +
> +static const struct clk_ops clk_sccg_pll2_ops = {
> + .prepare = clk_pll1_prepare,
> + .unprepare = clk_pll1_unprepare,
> + .recalc_rate = clk_pll2_recalc_rate,
> + .round_rate = clk_pll2_round_rate,
> + .set_rate = clk_pll2_set_rate,
> +};
> +
> +struct clk *imx_clk_sccg_pll(const char *name,
> + const char *parent_name,
> + void __iomem *base,
> + enum imx_sccg_pll_type pll_type)
> +{
> + struct clk_sccg_pll *pll;
> + struct clk *clk;
> + struct clk_init_data init;
> +
> + pll = kzalloc(sizeof(*pll), GFP_KERNEL);
> + if (!pll)
> + return ERR_PTR(-ENOMEM);
> +
> + pll->base = base;
> + init.name = name;
> + switch (pll_type) {
> + case SCCG_PLL1:
> + init.ops = &clk_sccg_pll1_ops;
> + break;
> + case SCCG_PLL2:
> + init.ops = &clk_sccg_pll2_ops;
> + break;
> + default:
> + kfree(pll);
> + return ERR_PTR(-EINVAL);
Do this case statement before allocating? So that kfree() isn't required
here?
> + }
> +
> + init.flags = 0;
> + init.parent_names = &parent_name;
> + init.num_parents = 1;
> +
> + pll->hw.init = &init;
> +
> + clk = clk_register(NULL, &pll->hw);
Any chance to use clk_hw based registration APIs?
> + if (IS_ERR(clk))
> + kfree(pll);
> +
> + return clk;
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