drivers/spi/tegra20_slink.c

// SPDX-License-Identifier: GPL-2.0
/*
 * NVIDIA Tegra SPI-SLINK controller
 *
 * Copyright (c) 2010-2013 NVIDIA Corporation
 */

#include <dm.h>
#include <log.h>
#include <time.h>
#include <asm/global_data.h>
#include <asm/io.h>
#include <asm/arch/clock.h>
#include <asm/arch-tegra/clk_rst.h>
#include <spi.h>
#include <fdtdec.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include "tegra_spi.h"

DECLARE_GLOBAL_DATA_PTR;

/* COMMAND */
#define SLINK_CMD_ENB			BIT(31)
#define SLINK_CMD_GO			BIT(30)
#define SLINK_CMD_M_S			BIT(28)
#define SLINK_CMD_IDLE_SCLK_DRIVE_LOW	(0 << 24)
#define SLINK_CMD_IDLE_SCLK_DRIVE_HIGH	BIT(24)
#define SLINK_CMD_IDLE_SCLK_PULL_LOW	(2 << 24)
#define SLINK_CMD_IDLE_SCLK_PULL_HIGH	(3 << 24)
#define SLINK_CMD_IDLE_SCLK_MASK	(3 << 24)
#define SLINK_CMD_CK_SDA		BIT(21)
#define SLINK_CMD_CS_POL		BIT(13)
#define SLINK_CMD_CS_VAL		BIT(12)
#define SLINK_CMD_CS_SOFT		BIT(11)
#define SLINK_CMD_BIT_LENGTH		BIT(4)
#define SLINK_CMD_BIT_LENGTH_MASK	GENMASK(4, 0)
/* COMMAND2 */
#define SLINK_CMD2_TXEN			BIT(30)
#define SLINK_CMD2_RXEN			BIT(31)
#define SLINK_CMD2_SS_EN		BIT(18)
#define SLINK_CMD2_SS_EN_SHIFT		18
#define SLINK_CMD2_SS_EN_MASK		GENMASK(19, 18)
#define SLINK_CMD2_CS_ACTIVE_BETWEEN	BIT(17)
/* STATUS */
#define SLINK_STAT_BSY			BIT(31)
#define SLINK_STAT_RDY			BIT(30)
#define SLINK_STAT_ERR			BIT(29)
#define SLINK_STAT_RXF_FLUSH		BIT(27)
#define SLINK_STAT_TXF_FLUSH		BIT(26)
#define SLINK_STAT_RXF_OVF		BIT(25)
#define SLINK_STAT_TXF_UNR		BIT(24)
#define SLINK_STAT_RXF_EMPTY		BIT(23)
#define SLINK_STAT_RXF_FULL		BIT(22)
#define SLINK_STAT_TXF_EMPTY		BIT(21)
#define SLINK_STAT_TXF_FULL		BIT(20)
#define SLINK_STAT_TXF_OVF		BIT(19)
#define SLINK_STAT_RXF_UNR		BIT(18)
#define SLINK_STAT_CUR_BLKCNT		BIT(15)
/* STATUS2 */
#define SLINK_STAT2_RXF_FULL_CNT	BIT(16)
#define SLINK_STAT2_TXF_FULL_CNT	BIT(0)

#define SPI_TIMEOUT		1000
#define TEGRA_SPI_MAX_FREQ	52000000

struct spi_regs {
	u32 command;	/* SLINK_COMMAND_0 register  */
	u32 command2;	/* SLINK_COMMAND2_0 reg */
	u32 status;	/* SLINK_STATUS_0 register */
	u32 reserved;	/* Reserved offset 0C */
	u32 mas_data;	/* SLINK_MAS_DATA_0 reg */
	u32 slav_data;	/* SLINK_SLAVE_DATA_0 reg */
	u32 dma_ctl;	/* SLINK_DMA_CTL_0 register */
	u32 status2;	/* SLINK_STATUS2_0 reg */
	u32 rsvd[56];	/* 0x20 to 0xFF reserved */
	u32 tx_fifo;	/* SLINK_TX_FIFO_0 reg off 100h */
	u32 rsvd2[31];	/* 0x104 to 0x17F reserved */
	u32 rx_fifo;	/* SLINK_RX_FIFO_0 reg off 180h */
};

struct tegra30_spi_priv {
	struct spi_regs *regs;
	unsigned int freq;
	unsigned int mode;
	int periph_id;
	int valid;
	int last_transaction_us;
};

struct tegra_spi_slave {
	struct spi_slave slave;
	struct tegra30_spi_priv *ctrl;
};

static int tegra30_spi_of_to_plat(struct udevice *bus)
{
	struct tegra_spi_plat *plat = dev_get_plat(bus);
	const void *blob = gd->fdt_blob;
	int node = dev_of_offset(bus);

	plat->base = dev_read_addr(bus);
	plat->periph_id = clock_decode_periph_id(bus);

	if (plat->periph_id == PERIPH_ID_NONE) {
		debug("%s: could not decode periph id %d\n", __func__,
		      plat->periph_id);
		return -FDT_ERR_NOTFOUND;
	}

	/* Use 500KHz as a suitable default */
	plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
					500000);
	plat->deactivate_delay_us = fdtdec_get_int(blob, node,
					"spi-deactivate-delay", 0);
	debug("%s: base=%#08lx, periph_id=%d, max-frequency=%d, deactivate_delay=%d\n",
	      __func__, plat->base, plat->periph_id, plat->frequency,
	      plat->deactivate_delay_us);

	return 0;
}

static int tegra30_spi_probe(struct udevice *bus)
{
	struct tegra_spi_plat *plat = dev_get_plat(bus);
	struct tegra30_spi_priv *priv = dev_get_priv(bus);

	priv->regs = (struct spi_regs *)plat->base;

	priv->last_transaction_us = timer_get_us();
	priv->freq = plat->frequency;
	priv->periph_id = plat->periph_id;

	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH,
			       priv->freq);

	return 0;
}

static int tegra30_spi_claim_bus(struct udevice *dev)
{
	struct udevice *bus = dev->parent;
	struct tegra30_spi_priv *priv = dev_get_priv(bus);
	struct spi_regs *regs = priv->regs;
	u32 reg;

	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH,
			       priv->freq);

	/* Clear stale status here */
	reg = SLINK_STAT_RDY | SLINK_STAT_RXF_FLUSH | SLINK_STAT_TXF_FLUSH | \
		SLINK_STAT_RXF_UNR | SLINK_STAT_TXF_OVF;
	writel(reg, &regs->status);
	debug("%s: STATUS = %08x\n", __func__, readl(&regs->status));

	/* Set master mode and sw controlled CS */
	reg = readl(&regs->command);
	reg |= SLINK_CMD_M_S | SLINK_CMD_CS_SOFT;
	writel(reg, &regs->command);
	debug("%s: COMMAND = %08x\n", __func__, readl(&regs->command));

	return 0;
}

static void spi_cs_activate(struct udevice *dev)
{
	struct udevice *bus = dev->parent;
	struct tegra_spi_plat *pdata = dev_get_plat(bus);
	struct tegra30_spi_priv *priv = dev_get_priv(bus);

	/* If it's too soon to do another transaction, wait */
	if (pdata->deactivate_delay_us &&
	    priv->last_transaction_us) {
		ulong delay_us;		/* The delay completed so far */
		delay_us = timer_get_us() - priv->last_transaction_us;
		if (delay_us < pdata->deactivate_delay_us)
			udelay(pdata->deactivate_delay_us - delay_us);
	}

	/* CS is negated on Tegra, so drive a 1 to get a 0 */
	setbits_le32(&priv->regs->command, SLINK_CMD_CS_VAL);
}

static void spi_cs_deactivate(struct udevice *dev)
{
	struct udevice *bus = dev->parent;
	struct tegra_spi_plat *pdata = dev_get_plat(bus);
	struct tegra30_spi_priv *priv = dev_get_priv(bus);

	/* CS is negated on Tegra, so drive a 0 to get a 1 */
	clrbits_le32(&priv->regs->command, SLINK_CMD_CS_VAL);

	/* Remember time of this transaction so we can honour the bus delay */
	if (pdata->deactivate_delay_us)
		priv->last_transaction_us = timer_get_us();
}

static int tegra30_spi_xfer(struct udevice *dev, unsigned int bitlen,
			    const void *data_out, void *data_in,
			    unsigned long flags)
{
	struct udevice *bus = dev->parent;
	struct tegra30_spi_priv *priv = dev_get_priv(bus);
	struct spi_regs *regs = priv->regs;
	u32 reg, tmpdout, tmpdin = 0;
	const u8 *dout = data_out;
	u8 *din = data_in;
	int num_bytes, overflow;
	int ret = 0;

	debug("%s: slave %u:%u dout %p din %p bitlen %u\n",
	      __func__, dev_seq(bus), spi_chip_select(dev), dout, din, bitlen);

	num_bytes = DIV_ROUND_UP(bitlen, 8);
	overflow = bitlen % 8;

	reg = readl(&regs->status);
	writel(reg, &regs->status);	/* Clear all SPI events via R/W */
	debug("%s entry: STATUS = %08x\n", __func__, reg);

	reg = readl(&regs->status2);
	writel(reg, &regs->status2);	/* Clear all STATUS2 events via R/W */
	debug("%s entry: STATUS2 = %08x\n", __func__, reg);

	debug("%s entry: COMMAND = %08x\n", __func__, readl(&regs->command));

	clrsetbits_le32(&regs->command2, SLINK_CMD2_SS_EN_MASK,
			SLINK_CMD2_TXEN | SLINK_CMD2_RXEN |
			(spi_chip_select(dev) << SLINK_CMD2_SS_EN_SHIFT));
	debug("%s entry: COMMAND2 = %08x\n", __func__, readl(&regs->command2));

	if (flags & SPI_XFER_BEGIN)
		spi_cs_activate(dev);

	/* handle data in 32-bit chunks */
	while (num_bytes > 0) {
		int bytes;
		int is_read = 0;
		int tm, i;

		tmpdout = 0;
		bytes = (num_bytes > 4) ?  4 : num_bytes;

		if (dout != NULL) {
			for (i = 0; i < bytes; ++i)
				tmpdout = (tmpdout << 8) | dout[i];
			dout += bytes;
		}

		num_bytes -= bytes;

		if (overflow && !num_bytes)
			clrsetbits_le32(&regs->command, SLINK_CMD_BIT_LENGTH_MASK,
					(bytes - 1) * 8 + overflow - 1);
		else
			clrsetbits_le32(&regs->command, SLINK_CMD_BIT_LENGTH_MASK,
					bytes * 8 - 1);

		writel(tmpdout, &regs->tx_fifo);
		setbits_le32(&regs->command, SLINK_CMD_GO);

		/*
		 * Wait for SPI transmit FIFO to empty, or to time out.
		 * The RX FIFO status will be read and cleared last
		 */
		for (tm = 0, is_read = 0; tm < SPI_TIMEOUT; ++tm) {
			u32 status;

			status = readl(&regs->status);

			/* We can exit when we've had both RX and TX activity */
			if (is_read && (status & SLINK_STAT_TXF_EMPTY))
				break;

			if ((status & (SLINK_STAT_BSY | SLINK_STAT_RDY)) !=
					SLINK_STAT_RDY)
				tm++;

			else if (!(status & SLINK_STAT_RXF_EMPTY)) {
				tmpdin = readl(&regs->rx_fifo);
				is_read = 1;

				/* swap bytes read in */
				if (din != NULL) {
					for (i = bytes - 1; i >= 0; --i) {
						din[i] = tmpdin & 0xff;
						tmpdin >>= 8;
					}
					din += bytes;
				}
			}
		}

		if (tm >= SPI_TIMEOUT)
			ret = tm;

		/* clear ACK RDY, etc. bits */
		writel(readl(&regs->status), &regs->status);
	}

	if (flags & SPI_XFER_END)
		spi_cs_deactivate(dev);

	debug("%s: transfer ended. Value=%08x, status = %08x\n",
	      __func__, tmpdin, readl(&regs->status));

	if (ret) {
		printf("%s: timeout during SPI transfer, tm %d\n",
		       __func__, ret);
		return -1;
	}

	return 0;
}

static int tegra30_spi_set_speed(struct udevice *bus, uint speed)
{
	struct tegra_spi_plat *plat = dev_get_plat(bus);
	struct tegra30_spi_priv *priv = dev_get_priv(bus);

	if (speed > plat->frequency)
		speed = plat->frequency;
	priv->freq = speed;
	debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, priv->freq);

	return 0;
}

static int tegra30_spi_set_mode(struct udevice *bus, uint mode)
{
	struct tegra30_spi_priv *priv = dev_get_priv(bus);
	struct spi_regs *regs = priv->regs;
	u32 reg;

	reg = readl(&regs->command);

	/* Set CPOL and CPHA */
	reg &= ~(SLINK_CMD_IDLE_SCLK_MASK | SLINK_CMD_CK_SDA);
	if (mode & SPI_CPHA)
		reg |= SLINK_CMD_CK_SDA;

	if (mode & SPI_CPOL)
		reg |= SLINK_CMD_IDLE_SCLK_DRIVE_HIGH;
	else
		reg |= SLINK_CMD_IDLE_SCLK_DRIVE_LOW;

	writel(reg, &regs->command);

	priv->mode = mode;
	debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);

	return 0;
}

static const struct dm_spi_ops tegra30_spi_ops = {
	.claim_bus	= tegra30_spi_claim_bus,
	.xfer		= tegra30_spi_xfer,
	.set_speed	= tegra30_spi_set_speed,
	.set_mode	= tegra30_spi_set_mode,
	/*
	 * cs_info is not needed, since we require all chip selects to be
	 * in the device tree explicitly
	 */
};

static const struct udevice_id tegra30_spi_ids[] = {
	{ .compatible = "nvidia,tegra20-slink" },
	{ }
};

U_BOOT_DRIVER(tegra30_spi) = {
	.name	= "tegra20_slink",
	.id	= UCLASS_SPI,
	.of_match = tegra30_spi_ids,
	.ops	= &tegra30_spi_ops,
	.of_to_plat = tegra30_spi_of_to_plat,
	.plat_auto	= sizeof(struct tegra_spi_plat),
	.priv_auto	= sizeof(struct tegra30_spi_priv),
	.probe	= tegra30_spi_probe,
};