path: root/drivers/net/wireless/microchip/wilc1000/spi.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2012 - 2018 Microchip Technology Inc., and its subsidiaries.
 * All rights reserved.
 */

#include <linux/clk.h>
#include <linux/spi/spi.h>
#include <linux/crc7.h>
#include <linux/crc-itu-t.h>
#include <linux/gpio/consumer.h>

#include "netdev.h"
#include "cfg80211.h"

#define SPI_MODALIAS		"wilc1000_spi"

static bool enable_crc7;	/* protect SPI commands with CRC7 */
module_param(enable_crc7, bool, 0644);
MODULE_PARM_DESC(enable_crc7,
		 "Enable CRC7 checksum to protect command transfers\n"
		 "\t\t\tagainst corruption during the SPI transfer.\n"
		 "\t\t\tCommand transfers are short and the CPU-cycle cost\n"
		 "\t\t\tof enabling this is small.");

static bool enable_crc16;	/* protect SPI data with CRC16 */
module_param(enable_crc16, bool, 0644);
MODULE_PARM_DESC(enable_crc16,
		 "Enable CRC16 checksum to protect data transfers\n"
		 "\t\t\tagainst corruption during the SPI transfer.\n"
		 "\t\t\tData transfers can be large and the CPU-cycle cost\n"
		 "\t\t\tof enabling this may be substantial.");

/*
 * For CMD_SINGLE_READ and CMD_INTERNAL_READ, WILC may insert one or
 * more zero bytes between the command response and the DATA Start tag
 * (0xf3).  This behavior appears to be undocumented in "ATWILC1000
 * USER GUIDE" (https://tinyurl.com/4hhshdts) but we have observed 1-4
 * zero bytes when the SPI bus operates at 48MHz and none when it
 * operates at 1MHz.
 */
#define WILC_SPI_RSP_HDR_EXTRA_DATA	8

struct wilc_spi {
	bool isinit;		/* true if wilc_spi_init was successful */
	bool probing_crc;	/* true if we're probing chip's CRC config */
	bool crc7_enabled;	/* true if crc7 is currently enabled */
	bool crc16_enabled;	/* true if crc16 is currently enabled */
	struct wilc_gpios {
		struct gpio_desc *enable;	/* ENABLE GPIO or NULL */
		struct gpio_desc *reset;	/* RESET GPIO or NULL */
	} gpios;
};

static const struct wilc_hif_func wilc_hif_spi;

static int wilc_spi_reset(struct wilc *wilc);
static int wilc_spi_configure_bus_protocol(struct wilc *wilc);
static int wilc_validate_chipid(struct wilc *wilc);

/********************************************
 *
 *      Spi protocol Function
 *
 ********************************************/

#define CMD_DMA_WRITE				0xc1
#define CMD_DMA_READ				0xc2
#define CMD_INTERNAL_WRITE			0xc3
#define CMD_INTERNAL_READ			0xc4
#define CMD_TERMINATE				0xc5
#define CMD_REPEAT				0xc6
#define CMD_DMA_EXT_WRITE			0xc7
#define CMD_DMA_EXT_READ			0xc8
#define CMD_SINGLE_WRITE			0xc9
#define CMD_SINGLE_READ				0xca
#define CMD_RESET				0xcf

#define SPI_RETRY_MAX_LIMIT			10
#define SPI_ENABLE_VMM_RETRY_LIMIT		2

/* SPI response fields (section 11.1.2 in ATWILC1000 User Guide): */
#define RSP_START_FIELD				GENMASK(7, 4)
#define RSP_TYPE_FIELD				GENMASK(3, 0)

/* SPI response values for the response fields: */
#define RSP_START_TAG				0xc
#define RSP_TYPE_FIRST_PACKET			0x1
#define RSP_TYPE_INNER_PACKET			0x2
#define RSP_TYPE_LAST_PACKET			0x3
#define RSP_STATE_NO_ERROR			0x00

#define PROTOCOL_REG_PKT_SZ_MASK		GENMASK(6, 4)
#define PROTOCOL_REG_CRC16_MASK			GENMASK(3, 3)
#define PROTOCOL_REG_CRC7_MASK			GENMASK(2, 2)

/*
 * The SPI data packet size may be any integer power of two in the
 * range from 256 to 8192 bytes.
 */
#define DATA_PKT_LOG_SZ_MIN			8	/* 256 B */
#define DATA_PKT_LOG_SZ_MAX			13	/* 8 KiB */

/*
 * Select the data packet size (log2 of number of bytes): Use the
 * maximum data packet size.  We only retransmit complete packets, so
 * there is no benefit from using smaller data packets.
 */
#define DATA_PKT_LOG_SZ				DATA_PKT_LOG_SZ_MAX
#define DATA_PKT_SZ				(1 << DATA_PKT_LOG_SZ)

#define WILC_SPI_COMMAND_STAT_SUCCESS		0
#define WILC_GET_RESP_HDR_START(h)		(((h) >> 4) & 0xf)

struct wilc_spi_cmd <