RE: [v6 2/2] clk: ls1028a: Add clock driver for Display output interface

[Wen He]

> -----Original Message-----
> From: Leo Li <leoyang.li@xxxxxxx>
> Sent: 2019年11月6日 5:11
> To: Wen He <wen.he_1@xxxxxxx>; linux-devel@xxxxxxxxxxxxxxxxxx; Michael
> Turquette <mturquette@xxxxxxxxxxxx>; Stephen Boyd <sboyd@xxxxxxxxxx>;
> Rob Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>;
> devicetree@xxxxxxxxxxxxxxx; linux-clk@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Cc: Wen He <wen.he_1@xxxxxxx>
> Subject: RE: [v6 2/2] clk: ls1028a: Add clock driver for Display output interface
> 
> 
> 
> > -----Original Message-----
> > From: Wen He <wen.he_1@xxxxxxx>
> > Sent: Tuesday, November 5, 2019 3:02 AM
> > To: linux-devel@xxxxxxxxxxxxxxxxxx; Michael Turquette
> > <mturquette@xxxxxxxxxxxx>; Stephen Boyd <sboyd@xxxxxxxxxx>; Rob
> > Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>;
> Leo
> > Li <leoyang.li@xxxxxxx>; devicetree@xxxxxxxxxxxxxxx; linux-
> > clk@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > Cc: Wen He <wen.he_1@xxxxxxx>
> > Subject: [v6 2/2] clk: ls1028a: Add clock driver for Display output
> > interface
> >
> > 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@xxxxxxx>
> > ---
> > change in v6:
> >         - Add get the best loop multiplication divider from DTS.
> >
> >  drivers/clk/Kconfig      |  10 ++
> >  drivers/clk/Makefile     |   1 +
> >  drivers/clk/clk-plldig.c | 294
> > +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 305 insertions(+)
> >  create mode 100644 drivers/clk/clk-plldig.c
> >
> > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index
> > 0530bebfc25a..9f6b0196c604 100644
> > --- a/drivers/clk/Kconfig
> > +++ b/drivers/clk/Kconfig
> > @@ -218,6 +218,16 @@ config CLK_QORIQ
> >  	  This adds the clock driver support for Freescale QorIQ platforms
> >  	  using common clock framework.
> >
> > +config CLK_LS1028A_PLLDIG
> > +        tristate "Clock driver for LS1028A Display output"
> > +        depends on ARCH_LAYERSCAPE || COMPILE_TEST
> > +        default ARCH_LAYERSCAPE
> > +        help
> > +          This driver support the Display output interfaces(LCD,
> > +DPHY) pixel
> > clocks
> > +          of the QorIQ Layerscape LS1028A, as implemented TSMC
> > + CLN28HPM
> > PLL. Not all
> > +          features of the PLL are currently supported by the driver. By
> default,
> > +          configured bypass mode with this PLL.
> > +
> >  config COMMON_CLK_XGENE
> >  	bool "Clock driver for APM XGene SoC"
> >  	default ARCH_XGENE
> > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index
> > 0138fb14e6f8..d23b7464aba8 100644
> > --- a/drivers/clk/Makefile
> > +++ b/drivers/clk/Makefile
> > @@ -45,6 +45,7 @@ obj-$(CONFIG_COMMON_CLK_OXNAS)		+=
> > clk-oxnas.o
> >  obj-$(CONFIG_COMMON_CLK_PALMAS)		+= clk-palmas.o
> >  obj-$(CONFIG_COMMON_CLK_PWM)		+= clk-pwm.o
> >  obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
> > +obj-$(CONFIG_CLK_LS1028A_PLLDIG)	+= clk-plldig.o
> 
> Wrong ordering.  This section of Makefile requires ordering by driver file
> name:
> 
> # hardware specific clock types
> # please keep this section sorted lexicographically by file path name
> 

Hi Leo,

Stephen once suggest the Kconfig variable name should be given a more
specific name like CLK_LS1028A_PLLDIG, so I have to changed it.

Hi Stephen,

How do you think?

Best Regards,
Wen

> >  obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
> >  obj-$(CONFIG_COMMON_CLK_HI655X)		+= clk-hi655x.o
> >  obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
> > diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c new
> > file mode
> > 100644 index 000000000000..57d8121990bd
> > --- /dev/null
> > +++ b/drivers/clk/clk-plldig.c
> > @@ -0,0 +1,294 @@
> > +// 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_REG_PLLDV            0x28
> > +#define PLLDIG_REG_PLLFM            0x2c
> > +#define PLLDIG_REG_PLLFD            0x30
> > +#define PLLDIG_REG_PLLCAL1          0x38
> > +#define PLLDIG_REG_PLLCAL2          0x3c
> > +#define PLLDIG_LOCK_MASK            BIT(2)
> > +#define PLLDIG_REG_FIELD_SSCGBYP    BIT(30)
> > +#define PLLDIG_REG_FIELD_FDEN       BIT(30)
> > +#define PLLDIG_REG_FIELD_DTHDIS     GENMASK(17, 16)
> > +#define PLLDIG_REG_FIELD_MULT       GENMASK(7, 0)
> > +#define PLLDIG_REG_FIELD_RFDPHI1    GENMASK(30, 25)
> > +
> > +/* Minimum output clock frequency, in Hz */ #define PHI1_MIN_FREQ
> > +27000000
> > +
> > +/* Maximum output clock frequency, in Hz */ #define PHI1_MAX_FREQ
> > +600000000
> > +
> > +/* Maximum of the divider */
> > +#define MAX_RFDPHI1          63
> > +
> > +/*
> > + * Clock configuration relationship between the PHI1
> > +frequency(fpll_phi) and
> > + * the output frequency of the PLL is determined by the PLLDV,
> > +according to
> > + * the following equation:
> > + * fpll_phi = (pll_ref * mfd) / div_rfdphi1  */ struct
> > +plldig_phi1_param {
> > +	unsigned long rate;
> > +	unsigned int rfdphi1;
> > +	unsigned int mfd;
> > +};
> > +
> > +static const struct clk_parent_data parent_data[] = {
> > +	{.index = 0},
> > +};
> > +
> > +struct clk_plldig {
> > +	struct clk_hw hw;
> > +	void __iomem *regs;
> > +	unsigned int mfd;
> > +};
> > +
> > +#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_REG_FIELD_SSCGBYP;
> > +	writel(val, data->regs + PLLDIG_REG_PLLFM);
> > +
> > +	val = readl(data->regs + PLLDIG_REG_PLLFD);
> > +	/* Disable dither and Sigma delta modulation in bypass mode */
> > +	val |= FIELD_PREP(PLLDIG_REG_FIELD_FDEN, 0x1) |
> > +	       FIELD_PREP(PLLDIG_REG_FIELD_DTHDIS, 0x3);
> > +
> > +	writel(val, data->regs + PLLDIG_REG_PLLFD);
> > +
> > +	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_REG_FIELD_SSCGBYP;
> > +	val |= FIELD_PREP(PLLDIG_REG_FIELD_SSCGBYP, 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) &
> > +			      PLLDIG_REG_FIELD_SSCGBYP);
> > +}
> > +
> > +static unsigned long plldig_recalc_rate(struct clk_hw *hw,
> > +		unsigned long parent_rate)
> > +{
> > +	struct clk_plldig *data = to_clk_plldig(hw);
> > +	u32 mult, div, val;
> > +
> > +	val = readl(data->regs + PLLDIG_REG_PLLDV);
> > +
> > +	/* Check if PLL is bypassed */
> > +	if (val & PLLDIG_REG_FIELD_SSCGBYP)
> > +		return parent_rate;
> > +
> > +	/* Checkout multiplication factor divider value */
> > +	mult = FIELD_GET(PLLDIG_REG_FIELD_MULT, val);
> > +
> > +	/* Checkout divider value of the output frequency */
> > +	div = FIELD_GET(PLLDIG_REG_FIELD_RFDPHI1, val);
> > +
> > +	return (parent_rate * mult) / div;
> > +}
> > +
> > +static int plldig_calc_target_rate(unsigned long target_rate,
> > +				   unsigned long parent_rate,
> > +				   struct plldig_phi1_param *phi1) {
> > +	unsigned int div, ret;
> > +	unsigned long round_rate;
> > +
> > +	/* Range limitation of the request target rate */
> > +	if (target_rate > PHI1_MAX_FREQ)
> > +		target_rate = PHI1_MAX_FREQ;
> > +	else if (target_rate < PHI1_MIN_FREQ)
> > +		target_rate = PHI1_MIN_FREQ;
> > +
> > +	/*
> > +	 * Firstly, check the request target rate whether is divisible
> > +	 * by the best VCO frequency.
> > +	 */
> > +	round_rate = parent_rate * phi1->mfd;
> > +	div = round_rate / target_rate;
> > +	if (!div || div > MAX_RFDPHI1)
> > +		return -EINVAL;
> > +
> > +	ret = round_rate % target_rate;
> > +	if (ret) {
> > +		/*
> > +		 * Rounded down the request target rate, VESA specifies
> > +		 * 0.5% pixel clock tolerance, therefore this algorithm
> > +		 * can able to compatible a lot of request rates within
> > +		 * range of the tolerance.
> > +		 */
> > +		round_rate += (target_rate / 2);
> > +		div = round_rate / target_rate;
> > +		if (!div || div > MAX_RFDPHI1)
> > +			return -EINVAL;
> > +	}
> > +
> > +	phi1->rfdphi1 = div;
> > +	phi1->rate = target_rate;
> > +
> > +	return 0;
> > +}
> > +
> > +static int plldig_determine_rate(struct clk_hw *hw,
> > +				 struct clk_rate_request *req)
> > +{
> > +	int ret;
> > +	unsigned long parent_rate;
> > +	struct clk_hw *parent;
> > +	struct plldig_phi1_param phi1_param;
> > +	struct clk_plldig *data = to_clk_plldig(hw);
> > +
> > +	if (!req->rate)
> > +		return -ERANGE;
> > +
> > +	phi1_param.mfd = data->mfd;
> > +	parent = clk_hw_get_parent(hw);
> > +	parent_rate = clk_hw_get_rate(parent);
> > +
> > +	ret = plldig_calc_target_rate(req->rate, parent_rate, &phi1_param);
> > +	if (ret)
> > +		return ret;
> > +
> > +	req->rate = phi1_param.rate;
> > +
> > +	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);
> > +	struct plldig_phi1_param phi1_param;
> > +	unsigned int val, cond;
> > +	int ret;
> > +
> > +	ret = plldig_calc_target_rate(rate, parent_rate, &phi1_param);
> > +	if (ret)
> > +		return ret;
> > +
> > +	val = readl(data->regs + PLLDIG_REG_PLLDV);
> > +	val = FIELD_PREP(PLLDIG_REG_FIELD_MULT, data->mfd) |
> > +	      FIELD_PREP(PLLDIG_REG_FIELD_RFDPHI1, phi1_param.rfdphi1);
> > +
> > +	writel(val, data->regs + PLLDIG_REG_PLLDV);
> > +
> > +	/* delay 200us make sure that old lock state is cleared */
> > +	udelay(200);
> > +
> > +	/* Wait until PLL is locked or timeout (maximum 1000 usecs) */
> > +	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_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);
> > +	if (IS_ERR(data->regs))
> > +		return PTR_ERR(data->regs);
> > +
> > +	 /*
> > +	  * Support to get the best loop multiplication divider value
> > +	  * from DTS file, since this PLL can't changed this value on
> > +	  * the fly, write the fixed value.
> > +	  */
> > +	ret = of_property_read_u32(dev->of_node, "best-mfd", &data-
> > >mfd);
> > +	if (ret)
> > +		data->mfd = 0x2c;
> > +
> > +	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;
> > +	}
> > +
> > +	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> > +					   &data->hw);
> > +}
> > +
> > +static const struct of_device_id plldig_clk_id[] = {
> > +	{ .compatible = "fsl,ls1028a-plldig"},
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, plldig_clk_id);
> > +
> > +static struct platform_driver plldig_clk_driver = {
> > +	.driver = {
> > +		.name = "plldig-clock",
> > +		.of_match_table = plldig_clk_id,
> > +	},
> > +	.probe = plldig_clk_probe,
> > +};
> > +module_platform_driver(plldig_clk_driver);
> > +
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_AUTHOR("Wen He <wen.he_1@xxxxxxx>");
> > MODULE_DESCRIPTION("LS1028A
> > +Display output interface pixel clock driver");
> > --
> > 2.17.1