drivers/mfd/atmel-smc.c

Source file repositories/reference/linux-study-clean/drivers/mfd/atmel-smc.c

File Facts

System
Linux kernel
Corpus path
drivers/mfd/atmel-smc.c
Extension
.c
Size
11107 bytes
Lines
359
Domain
Driver Families
Bucket
drivers/mfd
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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
/*
 * Atmel SMC (Static Memory Controller) helper functions.
 *
 * Copyright (C) 2017 Atmel
 * Copyright (C) 2017 Free Electrons
 *
 * Author: Boris Brezillon <boris.brezillon@free-electrons.com>
 */

#include <linux/bits.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/mod_devicetable.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/string.h>

#include <linux/mfd/syscon/atmel-smc.h>

/**
 * atmel_smc_cs_conf_init - initialize a SMC CS conf
 * @conf: the SMC CS conf to initialize
 *
 * Set all fields to 0 so that one can start defining a new config.
 */
void atmel_smc_cs_conf_init(struct atmel_smc_cs_conf *conf)
{
	memset(conf, 0, sizeof(*conf));
}
EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_init);

/**
 * atmel_smc_cs_encode_ncycles - encode a number of MCK clk cycles in the
 *				 format expected by the SMC engine
 * @ncycles: number of MCK clk cycles
 * @msbpos: position of the MSB part of the timing field
 * @msbwidth: width of the MSB part of the timing field
 * @msbfactor: factor applied to the MSB
 * @encodedval: param used to store the encoding result
 *
 * This function encodes the @ncycles value as described in the datasheet
 * (section "SMC Setup/Pulse/Cycle/Timings Register"). This is a generic
 * helper which called with different parameter depending on the encoding
 * scheme.
 *
 * If the @ncycles value is too big to be encoded, -ERANGE is returned and
 * the encodedval is contains the maximum val. Otherwise, 0 is returned.
 */
static int atmel_smc_cs_encode_ncycles(unsigned int ncycles,
				       unsigned int msbpos,
				       unsigned int msbwidth,
				       unsigned int msbfactor,
				       unsigned int *encodedval)
{
	unsigned int lsbmask = GENMASK(msbpos - 1, 0);
	unsigned int msbmask = GENMASK(msbwidth - 1, 0);
	unsigned int msb, lsb;
	int ret = 0;

	msb = ncycles / msbfactor;
	lsb = ncycles % msbfactor;

	if (lsb > lsbmask) {
		lsb = 0;
		msb++;
	}

	/*
	 * Let's just put the maximum we can if the requested setting does
	 * not fit in the register field.
	 * We still return -ERANGE in case the caller cares.
	 */
	if (msb > msbmask) {
		msb = msbmask;
		lsb = lsbmask;
		ret = -ERANGE;
	}

	*encodedval = (msb << msbpos) | lsb;

	return ret;
}

/**
 * atmel_smc_cs_conf_set_timing - set the SMC CS conf Txx parameter to a
 *				  specific value
 * @conf: SMC CS conf descriptor
 * @shift: the position of the Txx field in the TIMINGS register
 * @ncycles: value (expressed in MCK clk cycles) to assign to this Txx

Annotation

Implementation Notes