Initial import

1 files changed, 517 insertions, 0 deletions

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
new file mode 100644
index 000000000..37875cf94
--- /dev/null
+++ b/drivers/spi/spi-bcm2835.c
@@ -0,0 +1,517 @@
+/*
+ * Driver for Broadcom BCM2835 SPI Controllers
+ *
+ * Copyright (C) 2012 Chris Boot
+ * Copyright (C) 2013 Stephen Warren
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * This driver is inspired by:
+ * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
+ * spi-atmel.c, Copyright (C) 2006 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+
+/* SPI register offsets */
+#define BCM2835_SPI_CS			0x00
+#define BCM2835_SPI_FIFO		0x04
+#define BCM2835_SPI_CLK			0x08
+#define BCM2835_SPI_DLEN		0x0c
+#define BCM2835_SPI_LTOH		0x10
+#define BCM2835_SPI_DC			0x14
+
+/* Bitfields in CS */
+#define BCM2835_SPI_CS_LEN_LONG		0x02000000
+#define BCM2835_SPI_CS_DMA_LEN		0x01000000
+#define BCM2835_SPI_CS_CSPOL2		0x00800000
+#define BCM2835_SPI_CS_CSPOL1		0x00400000
+#define BCM2835_SPI_CS_CSPOL0		0x00200000
+#define BCM2835_SPI_CS_RXF		0x00100000
+#define BCM2835_SPI_CS_RXR		0x00080000
+#define BCM2835_SPI_CS_TXD		0x00040000
+#define BCM2835_SPI_CS_RXD		0x00020000
+#define BCM2835_SPI_CS_DONE		0x00010000
+#define BCM2835_SPI_CS_LEN		0x00002000
+#define BCM2835_SPI_CS_REN		0x00001000
+#define BCM2835_SPI_CS_ADCS		0x00000800
+#define BCM2835_SPI_CS_INTR		0x00000400
+#define BCM2835_SPI_CS_INTD		0x00000200
+#define BCM2835_SPI_CS_DMAEN		0x00000100
+#define BCM2835_SPI_CS_TA		0x00000080
+#define BCM2835_SPI_CS_CSPOL		0x00000040
+#define BCM2835_SPI_CS_CLEAR_RX		0x00000020
+#define BCM2835_SPI_CS_CLEAR_TX		0x00000010
+#define BCM2835_SPI_CS_CPOL		0x00000008
+#define BCM2835_SPI_CS_CPHA		0x00000004
+#define BCM2835_SPI_CS_CS_10		0x00000002
+#define BCM2835_SPI_CS_CS_01		0x00000001
+
+#define BCM2835_SPI_POLLING_LIMIT_US	30
+#define BCM2835_SPI_TIMEOUT_MS		30000
+#define BCM2835_SPI_MODE_BITS	(SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
+				| SPI_NO_CS | SPI_3WIRE)
+
+#define DRV_NAME	"spi-bcm2835"
+
+struct bcm2835_spi {
+	void __iomem *regs;
+	struct clk *clk;
+	int irq;
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	int tx_len;
+	int rx_len;
+};
+
+static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg)
+{
+	return readl(bs->regs + reg);
+}
+
+static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned reg, u32 val)
+{
+	writel(val, bs->regs + reg);
+}
+
+static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs)
+{
+	u8 byte;
+
+	while ((bs->rx_len) &&
+	       (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD)) {
+		byte = bcm2835_rd(bs, BCM2835_SPI_FIFO);
+		if (bs->rx_buf)
+			*bs->rx_buf++ = byte;
+		bs->rx_len--;
+	}
+}
+
+static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs)
+{
+	u8 byte;
+
+	while ((bs->tx_len) &&
+	       (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_TXD)) {
+		byte = bs->tx_buf ? *bs->tx_buf++ : 0;
+		bcm2835_wr(bs, BCM2835_SPI_FIFO, byte);
+		bs->tx_len--;
+	}
+}
+
+static void bcm2835_spi_reset_hw(struct spi_master *master)
+{
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+	u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+
+	/* Disable SPI interrupts and transfer */
+	cs &= ~(BCM2835_SPI_CS_INTR |
+		BCM2835_SPI_CS_INTD |
+		BCM2835_SPI_CS_TA);
+	/* and reset RX/TX FIFOS */
+	cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX;
+
+	/* and reset the SPI_HW */
+	bcm2835_wr(bs, BCM2835_SPI_CS, cs);
+}
+
+static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+
+	/* Read as many bytes as possible from FIFO */
+	bcm2835_rd_fifo(bs);
+	/* Write as many bytes as possible to FIFO */
+	bcm2835_wr_fifo(bs);
+
+	/* based on flags decide if we can finish the transfer */
+	if (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE) {
+		/* Transfer complete - reset SPI HW */
+		bcm2835_spi_reset_hw(master);
+		/* wake up the framework */
+		complete(&master->xfer_completion);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
+					 struct spi_device *spi,
+					 struct spi_transfer *tfr,
+					 u32 cs,
+					 unsigned long xfer_time_us)
+{
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+	/* set timeout to 1 second of maximum polling */
+	unsigned long timeout = jiffies + HZ;
+
+	/* enable HW block without interrupts */
+	bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
+
+	/* loop until finished the transfer */
+	while (bs->rx_len) {
+		/* read from fifo as much as possible */
+		bcm2835_rd_fifo(bs);
+		/* fill in tx fifo as much as possible */
+		bcm2835_wr_fifo(bs);
+		/* if we still expect some data after the read,
+		 * check for a possible timeout
+		 */
+		if (bs->rx_len && time_after(jiffies, timeout)) {
+			/* Transfer complete - reset SPI HW */
+			bcm2835_spi_reset_hw(master);
+			/* and return timeout */
+			return -ETIMEDOUT;
+		}
+	}
+
+	/* Transfer complete - reset SPI HW */
+	bcm2835_spi_reset_hw(master);
+	/* and return without waiting for completion */
+	return 0;
+}
+
+static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
+					struct spi_device *spi,
+					struct spi_transfer *tfr,
+					u32 cs)
+{
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+
+	/* fill in fifo if we have gpio-cs
+	 * note that there have been rare events where the native-CS
+	 * flapped for <1us which may change the behaviour
+	 * with gpio-cs this does not happen, so it is implemented
+	 * only for this case
+	 */
+	if (gpio_is_valid(spi->cs_gpio)) {
+		/* enable HW block, but without interrupts enabled
+		 * this would triggern an immediate interrupt
+		 */
+		bcm2835_wr(bs, BCM2835_SPI_CS,
+			   cs | BCM2835_SPI_CS_TA);
+		/* fill in tx fifo as much as possible */
+		bcm2835_wr_fifo(bs);
+	}
+
+	/*
+	 * Enable the HW block. This will immediately trigger a DONE (TX
+	 * empty) interrupt, upon which we will fill the TX FIFO with the
+	 * first TX bytes. Pre-filling the TX FIFO here to avoid the
+	 * interrupt doesn't work:-(
+	 */
+	cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
+	bcm2835_wr(bs, BCM2835_SPI_CS, cs);
+
+	/* signal that we need to wait for completion */
+	return 1;
+}
+
+static int bcm2835_spi_transfer_one(struct spi_master *master,
+				    struct spi_device *spi,
+				    struct spi_transfer *tfr)
+{
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+	unsigned long spi_hz, clk_hz, cdiv;
+	unsigned long spi_used_hz, xfer_time_us;
+	u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+
+	/* set clock */
+	spi_hz = tfr->speed_hz;
+	clk_hz = clk_get_rate(bs->clk);
+
+	if (spi_hz >= clk_hz / 2) {
+		cdiv = 2; /* clk_hz/2 is the fastest we can go */
+	} else if (spi_hz) {
+		/* CDIV must be a multiple of two */
+		cdiv = DIV_ROUND_UP(clk_hz, spi_hz);
+		cdiv += (cdiv % 2);
+
+		if (cdiv >= 65536)
+			cdiv = 0; /* 0 is the slowest we can go */
+	} else {
+		cdiv = 0; /* 0 is the slowest we can go */
+	}
+	spi_used_hz = cdiv ? (clk_hz / cdiv) : (clk_hz / 65536);
+	bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
+
+	/* handle all the modes */
+	if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf))
+		cs |= BCM2835_SPI_CS_REN;
+	if (spi->mode & SPI_CPOL)
+		cs |= BCM2835_SPI_CS_CPOL;
+	if (spi->mode & SPI_CPHA)
+		cs |= BCM2835_SPI_CS_CPHA;
+
+	/* for gpio_cs set dummy CS so that no HW-CS get changed
+	 * we can not run this in bcm2835_spi_set_cs, as it does
+	 * not get called for cs_gpio cases, so we need to do it here
+	 */
+	if (gpio_is_valid(spi->cs_gpio) || (spi->mode & SPI_NO_CS))
+		cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
+
+	/* set transmit buffers and length */
+	bs->tx_buf = tfr->tx_buf;
+	bs->rx_buf = tfr->rx_buf;
+	bs->tx_len = tfr->len;
+	bs->rx_len = tfr->len;
+
+	/* calculate the estimated time in us the transfer runs */
+	xfer_time_us = tfr->len
+		* 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
+		* 1000000 / spi_used_hz;
+
+	/* for short requests run polling*/
+	if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)
+		return bcm2835_spi_transfer_one_poll(master, spi, tfr,
+						     cs, xfer_time_us);
+
+	return bcm2835_spi_transfer_one_irq(master, spi, tfr, cs);
+}
+
+static void bcm2835_spi_handle_err(struct spi_master *master,
+				   struct spi_message *msg)
+{
+	bcm2835_spi_reset_hw(master);
+}
+
+static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
+{
+	/*
+	 * we can assume that we are "native" as per spi_set_cs
+	 *   calling us ONLY when cs_gpio is not set
+	 * we can also assume that we are CS < 3 as per bcm2835_spi_setup
+	 *   we would not get called because of error handling there.
+	 * the level passed is the electrical level not enabled/disabled
+	 *   so it has to get translated back to enable/disable
+	 *   see spi_set_cs in spi.c for the implementation
+	 */
+
+	struct spi_master *master = spi->master;
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+	u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+	bool enable;
+
+	/* calculate the enable flag from the passed gpio_level */
+	enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level;
+
+	/* set flags for "reverse" polarity in the registers */
+	if (spi->mode & SPI_CS_HIGH) {
+		/* set the correct CS-bits */
+		cs |= BCM2835_SPI_CS_CSPOL;
+		cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
+	} else {
+		/* clean the CS-bits */
+		cs &= ~BCM2835_SPI_CS_CSPOL;
+		cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select);
+	}
+
+	/* select the correct chip_select depending on disabled/enabled */
+	if (enable) {
+		/* set cs correctly */
+		if (spi->mode & SPI_NO_CS) {
+			/* use the "undefined" chip-select */
+			cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
+		} else {
+			/* set the chip select */
+			cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01);
+			cs |= spi->chip_select;
+		}
+	} else {
+		/* disable CSPOL which puts HW-CS into deselected state */
+		cs &= ~BCM2835_SPI_CS_CSPOL;
+		/* use the "undefined" chip-select as precaution */
+		cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
+	}
+
+	/* finally set the calculated flags in SPI_CS */
+	bcm2835_wr(bs, BCM2835_SPI_CS, cs);
+}
+
+static int chip_match_name(struct gpio_chip *chip, void *data)
+{
+	return !strcmp(chip->label, data);
+}
+
+static int bcm2835_spi_setup(struct spi_device *spi)
+{
+	int err;
+	struct gpio_chip *chip;
+	/*
+	 * sanity checking the native-chipselects
+	 */
+	if (spi->mode & SPI_NO_CS)
+		return 0;
+	if (gpio_is_valid(spi->cs_gpio))
+		return 0;
+	if (spi->chip_select > 1) {
+		/* error in the case of native CS requested with CS > 1
+		 * officially there is a CS2, but it is not documented
+		 * which GPIO is connected with that...
+		 */
+		dev_err(&spi->dev,
+			"setup: only two native chip-selects are supported\n");
+		return -EINVAL;
+	}
+	/* now translate native cs to GPIO */
+
+	/* get the gpio chip for the base */
+	chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
+	if (!chip)
+		return 0;
+
+	/* and calculate the real CS */
+	spi->cs_gpio = chip->base + 8 - spi->chip_select;
+
+	/* and set up the "mode" and level */
+	dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",
+		 spi->chip_select, spi->cs_gpio);
+
+	/* set up GPIO as output and pull to the correct level */
+	err = gpio_direction_output(spi->cs_gpio,
+				    (spi->mode & SPI_CS_HIGH) ? 0 : 1);
+	if (err) {
+		dev_err(&spi->dev,
+			"could not set CS%i gpio %i as output: %i",
+			spi->chip_select, spi->cs_gpio, err);
+		return err;
+	}
+	/* the implementation of pinctrl-bcm2835 currently does not
+	 * set the GPIO value when using gpio_direction_output
+	 * so we are setting it here explicitly
+	 */
+	gpio_set_value(spi->cs_gpio, (spi->mode & SPI_CS_HIGH) ? 0 : 1);
+
+	return 0;
+}
+
+static int bcm2835_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct bcm2835_spi *bs;
+	struct resource *res;
+	int err;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*bs));
+	if (!master) {
+		dev_err(&pdev->dev, "spi_alloc_master() failed\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, master);
+
+	master->mode_bits = BCM2835_SPI_MODE_BITS;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->num_chipselect = 3;
+	master->setup = bcm2835_spi_setup;
+	master->set_cs = bcm2835_spi_set_cs;
+	master->transfer_one = bcm2835_spi_transfer_one;
+	master->handle_err = bcm2835_spi_handle_err;
+	master->dev.of_node = pdev->dev.of_node;
+
+	bs = spi_master_get_devdata(master);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bs->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(bs->regs)) {
+		err = PTR_ERR(bs->regs);
+		goto out_master_put;
+	}
+
+	bs->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(bs->clk)) {
+		err = PTR_ERR(bs->clk);
+		dev_err(&pdev->dev, "could not get clk: %d\n", err);
+		goto out_master_put;
+	}
+
+	bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+	if (bs->irq <= 0) {
+		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
+		err = bs->irq ? bs->irq : -ENODEV;
+		goto out_master_put;
+	}
+
+	clk_prepare_enable(bs->clk);
+
+	err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0,
+			       dev_name(&pdev->dev), master);
+	if (err) {
+		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	/* initialise the hardware with the default polarities */
+	bcm2835_wr(bs, BCM2835_SPI_CS,
+		   BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err) {
+		dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	return 0;
+
+out_clk_disable:
+	clk_disable_unprepare(bs->clk);
+out_master_put:
+	spi_master_put(master);
+	return err;
+}
+
+static int bcm2835_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct bcm2835_spi *bs = spi_master_get_devdata(master);
+
+	/* Clear FIFOs, and disable the HW block */
+	bcm2835_wr(bs, BCM2835_SPI_CS,
+		   BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+
+	clk_disable_unprepare(bs->clk);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835_spi_match[] = {
+	{ .compatible = "brcm,bcm2835-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bcm2835_spi_match);
+
+static struct platform_driver bcm2835_spi_driver = {
+	.driver		= {
+		.name		= DRV_NAME,
+		.of_match_table	= bcm2835_spi_match,
+	},
+	.probe		= bcm2835_spi_probe,
+	.remove		= bcm2835_spi_remove,
+};
+module_platform_driver(bcm2835_spi_driver);
+
+MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835");
+MODULE_AUTHOR("Chris Boot <bootc@bootc.net>");
+MODULE_LICENSE("GPL v2");