path: root/drivers/net/dsa/sja1105/sja1105_spi.c

// SPDX-License-Identifier: BSD-3-Clause
/* Copyright (c) 2016-2018, NXP Semiconductors
 * Copyright (c) 2018, Sensor-Technik Wiedemann GmbH
 * Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
 */
#include <linux/spi/spi.h>
#include <linux/packing.h>
#include "sja1105.h"

#define SJA1105_SIZE_RESET_CMD		4
#define SJA1105_SIZE_SPI_MSG_HEADER	4
#define SJA1105_SIZE_SPI_MSG_MAXLEN	(64 * 4)

struct sja1105_chunk {
	u8	*buf;
	size_t	len;
	u64	reg_addr;
};

static void
sja1105_spi_message_pack(void *buf, const struct sja1105_spi_message *msg)
{
	const int size = SJA1105_SIZE_SPI_MSG_HEADER;

	memset(buf, 0, size);

	sja1105_pack(buf, &msg->access,     31, 31, size);
	sja1105_pack(buf, &msg->read_count, 30, 25, size);
	sja1105_pack(buf, &msg->address,    24,  4, size);
}

#define sja1105_hdr_xfer(xfers, chunk) \
	((xfers) + 2 * (chunk))
#define sja1105_chunk_xfer(xfers, chunk) \
	((xfers) + 2 * (chunk) + 1)
#define sja1105_hdr_buf(hdr_bufs, chunk) \
	((hdr_bufs) + (chunk) * SJA1105_SIZE_SPI_MSG_HEADER)

/* If @rw is:
 * - SPI_WRITE: creates and sends an SPI write message at absolute
 *		address reg_addr, taking @len bytes from *buf
 * - SPI_READ:  creates and sends an SPI read message from absolute
 *		address reg_addr, writing @len bytes into *buf
 */
static int sja1105_xfer(const struct sja1105_private *priv,
			sja1105_spi_rw_mode_t rw, u64 reg_addr, u8 *buf,
			size_t len, struct ptp_system_timestamp *ptp_sts)
{
	struct sja1105_chunk chunk = {
		.len = min_t(size_t, len, SJA1105_SIZE_SPI_MSG_MAXLEN),
		.reg_addr = reg_addr,
		.buf = buf,
	};
	struct spi_device *spi = priv->spidev;
	struct spi_transfer *xfers;
	int num_chunks;
	int rc, i = 0;
	u8 *hdr_bufs;

	num_chunks = DIV_ROUND_UP(len, SJA1105_SIZE_SPI_MSG_MAXLEN);

	/* One transfer for each message header, one for each message
	 * payload (chunk).
	 */
	xfers = kcalloc(2 * num_chunks, sizeof(struct spi_transfer),
			GFP_KERNEL);
	if (!xfers)
		return -ENOMEM;

	/* Packed buffers for the num_chunks SPI message headers,
	 * stored as a contiguous array
	 */
	hdr_bufs = kcalloc(num_chunks, SJA1105_SIZE_SPI_MSG_HEADER,
			   GFP_KERNEL);
	if (!hdr_bufs) {
		kfree(xfers);
		return -ENOMEM;
	}

	for (i = 0; i < num_chunks; i++) {
		struct spi_transfer *chunk_xfer = sja1105_chunk_xfer(xfers, i);
		struct spi_transfer *hdr_xfer = sja1105_hdr_xfer(xfers, i);
		u8 *hdr_buf = sja1105_hdr_buf(hdr_bufs, i);
		struct spi_transfer *ptp_sts_xfer;
		struct sja1105_spi_message msg;

		/* Populate the transfer's header buffer */
		msg.address = chunk.reg_addr;
		msg.access = rw;
		if (rw == SPI_READ)
			msg.read_count = chunk.len / 4;
		else
			/* Ignored */
			msg.read_count = 0;
		sja1105_spi_message_pack(hdr_buf, &msg);
		hdr_xfer->tx_buf = hdr_buf;
		hdr_xfer->len = SJA1105_SIZE_SPI_MSG_HEADER;

		/* Populate the transfer's data buffer */
		if (rw == SPI_READ)
			chunk_xfer->rx_buf = chunk.buf;
		else
			chunk_xfer->tx_buf = chunk.buf;
		chunk_xfer->len = chunk.len;

		/* Request timestamping for the transfer. Instead of letting
		 * callers specify which byte they want to timestamp, we can
		 * make certain assumptions:
		 * - A read operation will request a software timestamp when
		 *   what's being read is the PTP time. That is snapshotted by
		 *   the switch hardware at the end of the command portion
		 *   (hdr_xfer).
		 * - A write operation will request a software timestamp on
		 *   actions that modify the PTP time. Taking clock stepping as
		 *   an example, the switch writes the PTP time at the end of
		 *   the data portion (chunk_xfer).
		 */
		if (rw == SPI_READ)
			ptp_sts_xfer = hdr_xfer;
		else
			ptp_sts_xfer = chunk_xfer;
		ptp_sts_xfer->ptp_sts_word_pre = ptp_sts_xfer->len - 1;
		ptp_sts_xfer->ptp_sts_word_post = ptp_sts_xfer->len - 1;
		ptp_sts_xfer->ptp_sts = ptp_sts;

		/* Calculate next chunk */
		chunk.buf += chunk.len;
		chunk.reg_addr += chunk.len / 4;
		chunk.len = min_t(size_t, (ptrdiff_t)(buf + len - chunk.buf),
				  SJA1105_SIZE_SPI_MSG_MAXLEN);

		/* De-assert the chip select after each chunk. */
		if (chunk.len)
			chunk_xfer->cs_change = 1;
	}

	rc = spi_sync_transfer(spi, xfers, 2 * num_chunks);
	if (rc < 0)
		dev_err(&spi->dev, "SPI transfer failed: %d\n", rc);

	kfree(hdr_bufs);
	kfree(xfers);

	return rc;
}

int sja1105_xfer_buf(const struct sja1105_private *priv,
		     sja1105_spi_rw_mode_t rw, u64 reg_addr,
		     u8 *buf, size_t len)
{
	return sja1105_xfer(priv, rw, reg_addr, buf, len, NULL);
}

/* If @rw is:
 * - SPI_WRITE: creates and sends an SPI write message at absolute
 *		address reg_addr
 * - SPI_READ:  creates and sends an SPI read message from absolute
 *		address reg_addr
 *
 * The u64 *value is unpacked, meaning that it's stored in the native
 * CPU endianness and directly usable by software running on the core.
 */
int sja1105_xfer_u64(const struct sja1105_private *priv,
		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u64 *value,
		     struct ptp_system_timestamp *ptp_sts)
{
	u8 packed_buf[8];
	int rc;

	if (rw == SPI_WRITE)
		sja1105_pack(packed_buf, value, 63, 0, 8);

	rc = sja1105_xfer(priv, rw, reg_addr, packed_buf, 8, ptp_sts);

	if (rw == SPI_READ)
		sja1105_unpack(packed_buf, value, 63, 0, 8);

	return rc;
}

/* Same as above, but transfers only a 4 byte word */
int sja1105_xfer_u32(const struct sja1105_private *priv,
		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u32 *value,
		     struct ptp_system_timestamp *ptp_sts)
{
	u8 packed_buf[4];
	u64 tmp;
	int rc;

	if (rw == SPI_WRITE) {
		/* The packing API only supports u64 as CPU word size,
		 * so we need to convert.
		 */
		tmp = *value;
		sja1105_pack(packed_buf, &tmp, 31, 0, 4);
	}

	rc = sja1105_xfer(priv, rw, reg_addr, packed_buf, 4, ptp_sts);

	if (rw == SPI_READ) {
		sja1105_unpack(packed_buf, &tmp, 31, 0, 4);
		*value = tmp;
	}

	return rc;
}

static int sja1105et_reset_cmd(struct dsa_switch *ds)
{
	struct sja1105_private *priv = ds->priv;
	const struct sja1105_regs *regs = priv->info->regs;
	u8 packed_buf[SJA1105_SIZE_RESET_CMD] = {0};
	const int size = SJA1105_SIZE_RESET_CMD;
	u64 cold_rst = 1;

	sja1105_pack(packed_buf, &cold_rst,