drivers/clk/tegra/cvb.c

Source file repositories/reference/linux-study-clean/drivers/clk/tegra/cvb.c

File Facts

System
Linux kernel
Corpus path
drivers/clk/tegra/cvb.c
Extension
.c
Size
4002 bytes
Lines
143
Domain
Driver Families
Bucket
drivers/clk
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Utility functions for parsing Tegra CVB voltage tables
 *
 * Copyright (C) 2012-2019 NVIDIA Corporation.  All rights reserved.
 */
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/pm_opp.h>

#include "cvb.h"

/* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
static inline int get_cvb_voltage(int speedo, int s_scale,
				  const struct cvb_coefficients *cvb)
{
	int mv;

	/* apply only speedo scale: output mv = cvb_mv * v_scale */
	mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
	mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
	return mv;
}

static int round_cvb_voltage(int mv, int v_scale,
			     const struct rail_alignment *align)
{
	/* combined: apply voltage scale and round to cvb alignment step */
	int uv;
	int step = (align->step_uv ? : 1000) * v_scale;
	int offset = align->offset_uv * v_scale;

	uv = max(mv * 1000, offset) - offset;
	uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
	return uv / 1000;
}

enum {
	DOWN,
	UP
};

static int round_voltage(int mv, const struct rail_alignment *align, int up)
{
	if (align->step_uv) {
		int uv;

		uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
		uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
		return (uv * align->step_uv + align->offset_uv) / 1000;
	}
	return mv;
}

static int build_opp_table(struct device *dev, const struct cvb_table *table,
			   struct rail_alignment *align,
			   int speedo_value, unsigned long max_freq)
{
	int i, ret, dfll_mv, min_mv, max_mv;

	min_mv = round_voltage(table->min_millivolts, align, UP);
	max_mv = round_voltage(table->max_millivolts, align, DOWN);

	for (i = 0; i < MAX_DVFS_FREQS; i++) {
		const struct cvb_table_freq_entry *entry = &table->entries[i];

		if (!entry->freq || (entry->freq > max_freq))
			break;

		dfll_mv = get_cvb_voltage(speedo_value, table->speedo_scale,
					  &entry->coefficients);
		dfll_mv = round_cvb_voltage(dfll_mv, table->voltage_scale,
					    align);
		dfll_mv = clamp(dfll_mv, min_mv, max_mv);

		ret = dev_pm_opp_add(dev, entry->freq, dfll_mv * 1000);
		if (ret)
			return ret;
	}

	return 0;
}

/**
 * tegra_cvb_add_opp_table - build OPP table from Tegra CVB tables
 * @dev: the struct device * for which the OPP table is built
 * @tables: array of CVB tables
 * @count: size of the previously mentioned array
 * @align: parameters of the regulator step and offset
 * @process_id: process id of the HW module

Annotation

Implementation Notes