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Date: Fri, 13 Dec 2019 01:06:16 +0100
From: Michael Walle <michael@...le.cc>
To: Stephen Boyd <sboyd@...nel.org>, Li Yang <leoyang.li@....com>,
Mark Rutland <mark.rutland@....com>,
Michael Turquette <mturquette@...libre.com>,
Rob Herring <robh+dt@...nel.org>, Wen He <wen.he_1@....com>,
devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [v11 2/2] clk: ls1028a: Add clock driver for Display output interface
Am 12. Dezember 2019 23:18:16 MEZ schrieb Stephen Boyd <sboyd@...nel.org>:
>Quoting Wen He (2019-12-04 23:26:53)
>> Add clock driver for QorIQ LS1028A Display output interfaces(LCD,
>DPHY),
>> as implemented in TSMC CLN28HPM PLL, this PLL supports the
>programmable
>> integer division and range of the display output pixel clock's
>27-594MHz.
>>
>> Signed-off-by: Wen He <wen.he_1@....com>
>> Signed-off-by: Michael Walle <michael@...le.cc>
>
>Is Michael the author? SoB chain is backwards here.
the original driver was from Wen. I've just supplied some code and
the vco frequency stuff. so its basically a sob of us both.
-michael
>
>> diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c
>> new file mode 100644
>> index 000000000000..1942686f0254
>> --- /dev/null
>> +++ b/drivers/clk/clk-plldig.c
>> @@ -0,0 +1,297 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2019 NXP
>> + *
>> + * Clock driver for LS1028A Display output interfaces(LCD, DPHY).
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/device.h>
>> +#include <linux/module.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +#include <linux/bitfield.h>
>> +
>> +/* PLLDIG register offsets and bit masks */
>> +#define PLLDIG_REG_PLLSR 0x24
>> +#define PLLDIG_LOCK_MASK BIT(2)
>> +#define PLLDIG_REG_PLLDV 0x28
>> +#define PLLDIG_MFD_MASK GENMASK(7, 0)
>> +#define PLLDIG_RFDPHI1_MASK GENMASK(30, 25)
>> +#define PLLDIG_REG_PLLFM 0x2c
>> +#define PLLDIG_SSCGBYP_ENABLE BIT(30)
>> +#define PLLDIG_REG_PLLFD 0x30
>> +#define PLLDIG_FDEN BIT(30)
>> +#define PLLDIG_FRAC_MASK GENMASK(15, 0)
>> +#define PLLDIG_REG_PLLCAL1 0x38
>> +#define PLLDIG_REG_PLLCAL2 0x3c
>> +
>> +/* Range of the VCO frequencies, in Hz */
>> +#define PLLDIG_MIN_VCO_FREQ 650000000
>> +#define PLLDIG_MAX_VCO_FREQ 1300000000
>> +
>> +/* Range of the output frequencies, in Hz */
>> +#define PHI1_MIN_FREQ 27000000
>> +#define PHI1_MAX_FREQ 600000000
>> +
>> +/* Maximum value of the reduced frequency divider */
>> +#define MAX_RFDPHI1 63UL
>> +
>> +/* Best value of multiplication factor divider */
>> +#define PLLDIG_DEFAULT_MFD 44
>> +
>> +/*
>> + * Denominator part of the fractional part of the
>> + * loop multiplication factor.
>> + */
>> +#define MFDEN 20480
>> +
>> +static const struct clk_parent_data parent_data[] = {
>> + {.index = 0},
>
>Nitpick: Add spaces after { and before }
>
>> +};
>> +
>> +struct clk_plldig {
>> + struct clk_hw hw;
>> + void __iomem *regs;
>> + unsigned int vco_freq;
>> +};
>> +
>> +#define to_clk_plldig(_hw) container_of(_hw, struct clk_plldig,
>hw)
>> +
>> +static int plldig_enable(struct clk_hw *hw)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + u32 val;
>> +
>> + val = readl(data->regs + PLLDIG_REG_PLLFM);
>> + /*
>> + * Use Bypass mode with PLL off by default, the frequency
>overshoot
>> + * detector output was disable. SSCG Bypass mode should be
>enable.
>> + */
>> + val |= PLLDIG_SSCGBYP_ENABLE;
>> + writel(val, data->regs + PLLDIG_REG_PLLFM);
>> +
>> + return 0;
>> +}
>> +
>> +static void plldig_disable(struct clk_hw *hw)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + u32 val;
>> +
>> + val = readl(data->regs + PLLDIG_REG_PLLFM);
>> +
>> + val &= ~PLLDIG_SSCGBYP_ENABLE;
>> + val |= FIELD_PREP(PLLDIG_SSCGBYP_ENABLE, 0x0);
>> +
>> + writel(val, data->regs + PLLDIG_REG_PLLFM);
>> +}
>> +
>> +static int plldig_is_enabled(struct clk_hw *hw)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> +
>> + return (readl(data->regs + PLLDIG_REG_PLLFM) &
>
>Please drop useless parenthesis.
>
>> + PLLDIG_SSCGBYP_ENABLE);
>> +}
>> +
>> +static unsigned long plldig_recalc_rate(struct clk_hw *hw,
>> + unsigned long parent_rate)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + u32 val, rfdphi1;
>> +
>> + val = readl(data->regs + PLLDIG_REG_PLLDV);
>> +
>> + /* Check if PLL is bypassed */
>> + if (val & PLLDIG_SSCGBYP_ENABLE)
>> + return parent_rate;
>> +
>> + rfdphi1 = FIELD_GET(PLLDIG_RFDPHI1_MASK, val);
>> +
>> + /*
>> + * If RFDPHI1 has a value of 1 the VCO frequency is also
>divided by
>> + * one.
>> + */
>> + if (!rfdphi1)
>> + rfdphi1 = 1;
>> +
>> + return DIV_ROUND_UP(data->vco_freq, rfdphi1);
>> +}
>> +
>> +static unsigned long plldig_calc_target_div(unsigned long vco_freq,
>> + unsigned long
>target_rate)
>> +{
>> + unsigned long div;
>> +
>> + div = DIV_ROUND_CLOSEST(vco_freq, target_rate);
>> + div = max(1UL, div);
>> + div = min(div, MAX_RFDPHI1);
>
>Use clamp().
>
>> +
>> + return div;
>> +}
>> +
>> +static int plldig_determine_rate(struct clk_hw *hw,
>> + struct clk_rate_request *req)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + unsigned int div;
>> +
>> + if (req->rate < PHI1_MIN_FREQ)
>> + req->rate = PHI1_MIN_FREQ;
>> + if (req->rate > PHI1_MAX_FREQ)
>> + req->rate = PHI1_MAX_FREQ;
>
>Use clamp()
>
>> +
>> + div = plldig_calc_target_div(data->vco_freq, req->rate);
>> + req->rate = DIV_ROUND_UP(data->vco_freq, div);
>> +
>> + return 0;
>> +}
>> +
>> +static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
>> + unsigned long parent_rate)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + unsigned int val, cond;
>> + unsigned int rfdphi1;
>> +
>> + if (rate < PHI1_MIN_FREQ)
>> + rate = PHI1_MIN_FREQ;
>> + if (rate > PHI1_MAX_FREQ)
>> + rate = PHI1_MAX_FREQ;
>
>Use clamp()
>
>> +
>> + rfdphi1 = plldig_calc_target_div(data->vco_freq, rate);
>> +
>> + /* update the divider value */
>> + val = readl(data->regs + PLLDIG_REG_PLLDV);
>> + val &= ~PLLDIG_RFDPHI1_MASK;
>> + val |= FIELD_PREP(PLLDIG_RFDPHI1_MASK, rfdphi1);
>> + writel(val, data->regs + PLLDIG_REG_PLLDV);
>> +
>> + /* delay 200us make sure that old lock state is cleared */
>> + udelay(200);
>
>Please remove 'delay 200us' from the comment. Just say that we're
>waiting
>for old lock state to clear. It's clear from the code how much time it
>is.
>
>> +
>> + /* Wait until PLL is locked or timeout (maximum 1000 usecs)
>*/
>
>Drop the time. It's a millisecond.
>
>> + return readl_poll_timeout_atomic(data->regs +
>PLLDIG_REG_PLLSR, cond,
>> + cond & PLLDIG_LOCK_MASK, 0,
>> + USEC_PER_MSEC);
>> +}
>> +
>> +static const struct clk_ops plldig_clk_ops = {
>> + .enable = plldig_enable,
>> + .disable = plldig_disable,
>> + .is_enabled = plldig_is_enabled,
>> + .recalc_rate = plldig_recalc_rate,
>> + .determine_rate = plldig_determine_rate,
>> + .set_rate = plldig_set_rate,
>> +};
>> +
>> +static int plldig_init(struct clk_hw *hw)
>> +{
>> + struct clk_plldig *data = to_clk_plldig(hw);
>> + struct clk_hw *parent = clk_hw_get_parent(hw);
>> + unsigned long parent_rate = clk_hw_get_rate(parent);
>> + unsigned long val;
>> + unsigned long long lltmp;
>> + unsigned int mfd, fracdiv = 0;
>> +
>> + if (!parent)
>> + return -EINVAL;
>> +
>> + if (data->vco_freq) {
>> + mfd = data->vco_freq / parent_rate;
>> + lltmp = data->vco_freq % parent_rate;
>> + lltmp *= MFDEN;
>> + do_div(lltmp, parent_rate);
>> + fracdiv = lltmp;
>> + } else {
>> + mfd = PLLDIG_DEFAULT_MFD;
>> + data->vco_freq = parent_rate * mfd;
>> + }
>> +
>> + val = FIELD_PREP(PLLDIG_MFD_MASK, mfd);
>> + writel(val, data->regs + PLLDIG_REG_PLLDV);
>> +
>> + if (fracdiv) {
>> + val = FIELD_PREP(PLLDIG_FRAC_MASK, fracdiv);
>> + /* Enable fractional divider */
>
>Remove useless comment please. Or move above the if condition.
>
>> + val |= PLLDIG_FDEN;
>> + writel(val, data->regs + PLLDIG_REG_PLLFD);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int plldig_clk_probe(struct platform_device *pdev)
>> +{
>> + struct clk_plldig *data;
>> + struct resource *mem;
>> + struct device *dev = &pdev->dev;
>> + int ret;
>> +
>> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + data->regs = devm_ioremap_resource(dev, mem);
>
>We have devm_platform_ioremap_resource() for this now.
>
>> + if (IS_ERR(data->regs))
>> + return PTR_ERR(data->regs);
>> +
>> + data->hw.init = CLK_HW_INIT_PARENTS_DATA("dpclk",
>> + parent_data,
>> + &plldig_clk_ops,
>> + 0);
>> +
>> + ret = devm_clk_hw_register(dev, &data->hw);
>> + if (ret) {
>> + dev_err(dev, "failed to register %s clock\n",
>> + dev->of_node->name);
>> + return ret;
>> + }
>> +
>> + ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
>> + &data->hw);
>> + if (ret) {
>> + dev_err(dev, "unable to add clk provider\n");
>> + return ret;
>> + }
>> +
>> + /*
>> + * The frequency of the VCO cannot be changed during runtime.
>> + * Therefore, let the user specify a desired frequency.
>> + */
>> + if (!of_property_read_u32(dev->of_node, "fsl,vco-hz",
>> + &data->vco_freq)) {
>> + if (data->vco_freq < PLLDIG_MIN_VCO_FREQ ||
>> + data->vco_freq > PLLDIG_MAX_VCO_FREQ)
>> + return -EINVAL;
>> + }
>> +
>> + return plldig_init(&data->hw);
>> +}
>> +
>> +static const struct of_device_id plldig_clk_id[] = {
>> + { .compatible = "fsl,ls1028a-plldig"},
>
>Nitpick: Add a space before }
>
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(of, plldig_clk_id);
>> +
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