Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 531 insertions, 0 deletions

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
new file mode 100644
index 000000000..8ea7e31b8
--- /dev/null
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -0,0 +1,531 @@
+/*
+ * Driver for Broadcom BCM2835 auxiliary SPI Controllers
+ *
+ * the driver does not rely on the native chipselects at all
+ * but only uses the gpio type chipselects
+ *
+ * Based on: spi-bcm2835.c
+ *
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * 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_address.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/spinlock.h>
+
+/*
+ * spi register defines
+ *
+ * note there is garbage in the "official" documentation,
+ * so some data is taken from the file:
+ *   brcm_usrlib/dag/vmcsx/vcinclude/bcm2708_chip/aux_io.h
+ * inside of:
+ *   http://www.broadcom.com/docs/support/videocore/Brcm_Android_ICS_Graphics_Stack.tar.gz
+ */
+
+/* SPI register offsets */
+#define BCM2835_AUX_SPI_CNTL0	0x00
+#define BCM2835_AUX_SPI_CNTL1	0x04
+#define BCM2835_AUX_SPI_STAT	0x08
+#define BCM2835_AUX_SPI_PEEK	0x0C
+#define BCM2835_AUX_SPI_IO	0x20
+#define BCM2835_AUX_SPI_TXHOLD	0x30
+
+/* Bitfields in CNTL0 */
+#define BCM2835_AUX_SPI_CNTL0_SPEED	0xFFF00000
+#define BCM2835_AUX_SPI_CNTL0_SPEED_MAX	0xFFF
+#define BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT	20
+#define BCM2835_AUX_SPI_CNTL0_CS	0x000E0000
+#define BCM2835_AUX_SPI_CNTL0_POSTINPUT	0x00010000
+#define BCM2835_AUX_SPI_CNTL0_VAR_CS	0x00008000
+#define BCM2835_AUX_SPI_CNTL0_VAR_WIDTH	0x00004000
+#define BCM2835_AUX_SPI_CNTL0_DOUTHOLD	0x00003000
+#define BCM2835_AUX_SPI_CNTL0_ENABLE	0x00000800
+#define BCM2835_AUX_SPI_CNTL0_IN_RISING	0x00000400
+#define BCM2835_AUX_SPI_CNTL0_CLEARFIFO	0x00000200
+#define BCM2835_AUX_SPI_CNTL0_OUT_RISING	0x00000100
+#define BCM2835_AUX_SPI_CNTL0_CPOL	0x00000080
+#define BCM2835_AUX_SPI_CNTL0_MSBF_OUT	0x00000040
+#define BCM2835_AUX_SPI_CNTL0_SHIFTLEN	0x0000003F
+
+/* Bitfields in CNTL1 */
+#define BCM2835_AUX_SPI_CNTL1_CSHIGH	0x00000700
+#define BCM2835_AUX_SPI_CNTL1_TXEMPTY	0x00000080
+#define BCM2835_AUX_SPI_CNTL1_IDLE	0x00000040
+#define BCM2835_AUX_SPI_CNTL1_MSBF_IN	0x00000002
+#define BCM2835_AUX_SPI_CNTL1_KEEP_IN	0x00000001
+
+/* Bitfields in STAT */
+#define BCM2835_AUX_SPI_STAT_TX_LVL	0xFF000000
+#define BCM2835_AUX_SPI_STAT_RX_LVL	0x00FF0000
+#define BCM2835_AUX_SPI_STAT_TX_FULL	0x00000400
+#define BCM2835_AUX_SPI_STAT_TX_EMPTY	0x00000200
+#define BCM2835_AUX_SPI_STAT_RX_FULL	0x00000100
+#define BCM2835_AUX_SPI_STAT_RX_EMPTY	0x00000080
+#define BCM2835_AUX_SPI_STAT_BUSY	0x00000040
+#define BCM2835_AUX_SPI_STAT_BITCOUNT	0x0000003F
+
+/* timeout values */
+#define BCM2835_AUX_SPI_POLLING_LIMIT_US	30
+#define BCM2835_AUX_SPI_POLLING_JIFFIES		2
+
+struct bcm2835aux_spi {
+	void __iomem *regs;
+	struct clk *clk;
+	int irq;
+	u32 cntl[2];
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	int tx_len;
+	int rx_len;
+	int pending;
+};
+
+static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg)
+{
+	return readl(bs->regs + reg);
+}
+
+static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned reg,
+				 u32 val)
+{
+	writel(val, bs->regs + reg);
+}
+
+static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	int count = min(bs->rx_len, 3);
+
+	data = bcm2835aux_rd(bs, BCM2835_AUX_SPI_IO);
+	if (bs->rx_buf) {
+		switch (count) {
+		case 4:
+			*bs->rx_buf++ = (data >> 24) & 0xff;
+			/* fallthrough */
+		case 3:
+			*bs->rx_buf++ = (data >> 16) & 0xff;
+			/* fallthrough */
+		case 2:
+			*bs->rx_buf++ = (data >> 8) & 0xff;
+			/* fallthrough */
+		case 1:
+			*bs->rx_buf++ = (data >> 0) & 0xff;
+			/* fallthrough - no default */
+		}
+	}
+	bs->rx_len -= count;
+	bs->pending -= count;
+}
+
+static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	u8 byte;
+	int count;
+	int i;
+
+	/* gather up to 3 bytes to write to the FIFO */
+	count = min(bs->tx_len, 3);
+	data = 0;
+	for (i = 0; i < count; i++) {
+		byte = bs->tx_buf ? *bs->tx_buf++ : 0;
+		data |= byte << (8 * (2 - i));
+	}
+
+	/* and set the variable bit-length */
+	data |= (count * 8) << 24;
+
+	/* and decrement length */
+	bs->tx_len -= count;
+	bs->pending += count;
+
+	/* write to the correct TX-register */
+	if (bs->tx_len)
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_TXHOLD, data);
+	else
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_IO, data);
+}
+
+static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
+{
+	/* disable spi clearing fifo and interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, 0);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0,
+		      BCM2835_AUX_SPI_CNTL0_CLEARFIFO);
+}
+
+static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs)
+{
+	u32 stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
+
+	/* check if we have data to read */
+	for (; bs->rx_len && (stat & BCM2835_AUX_SPI_STAT_RX_LVL);
+	     stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT))
+		bcm2835aux_rd_fifo(bs);
+
+	/* check if we have data to write */
+	while (bs->tx_len &&
+	       (bs->pending < 12) &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+	}
+}
+
+static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* IRQ may be shared, so return if our interrupts are disabled */
+	if (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_CNTL1) &
+	      (BCM2835_AUX_SPI_CNTL1_TXEMPTY | BCM2835_AUX_SPI_CNTL1_IDLE)))
+		return IRQ_NONE;
+
+	/* do common fifo handling */
+	bcm2835aux_spi_transfer_helper(bs);
+
+	if (!bs->tx_len) {
+		/* disable tx fifo empty interrupt */
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
+			BCM2835_AUX_SPI_CNTL1_IDLE);
+	}
+
+	/* and if rx_len is 0 then disable interrupts and wake up completion */
+	if (!bs->rx_len) {
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+		complete(&master->xfer_completion);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int __bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					     struct spi_device *spi,
+					     struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* enable interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
+		BCM2835_AUX_SPI_CNTL1_TXEMPTY |
+		BCM2835_AUX_SPI_CNTL1_IDLE);
+
+	/* and wait for finish... */
+	return 1;
+}
+
+static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					   struct spi_device *spi,
+					   struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* fill in registers and fifos before enabling interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* fill in tx fifo with data before enabling interrupts */
+	while ((bs->tx_len) &&
+	       (bs->pending < 12) &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+	}
+
+	/* now run the interrupt mode */
+	return __bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+}
+
+static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
+					    struct spi_device *spi,
+					struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long timeout;
+
+	/* configure spi */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* set the timeout */
+	timeout = jiffies + BCM2835_AUX_SPI_POLLING_JIFFIES;
+
+	/* loop until finished the transfer */
+	while (bs->rx_len) {
+
+		/* do common fifo handling */
+		bcm2835aux_spi_transfer_helper(bs);
+
+		/* there is still data pending to read check the timeout */
+		if (bs->rx_len && time_after(jiffies, timeout)) {
+			dev_dbg_ratelimited(&spi->dev,
+					    "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
+					    jiffies - timeout,
+					    bs->tx_len, bs->rx_len);
+			/* forward to interrupt handler */
+			return __bcm2835aux_spi_transfer_one_irq(master,
+							       spi, tfr);
+		}
+	}
+
+	/* and return without waiting for completion */
+	return 0;
+}
+
+static int bcm2835aux_spi_transfer_one(struct spi_master *master,
+				       struct spi_device *spi,
+				       struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long spi_hz, clk_hz, speed;
+	unsigned long spi_used_hz;
+
+	/* calculate the registers to handle
+	 *
+	 * note that we use the variable data mode, which
+	 * is not optimal for longer transfers as we waste registers
+	 * resulting (potentially) in more interrupts when transferring
+	 * more than 12 bytes
+	 */
+
+	/* set clock */
+	spi_hz = tfr->speed_hz;
+	clk_hz = clk_get_rate(bs->clk);
+
+	if (spi_hz >= clk_hz / 2) {
+		speed = 0;
+	} else if (spi_hz) {
+		speed = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
+		if (speed >  BCM2835_AUX_SPI_CNTL0_SPEED_MAX)
+			speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	} else { /* the slowest we can go */
+		speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	}
+	/* mask out old speed from previous spi_transfer */
+	bs->cntl[0] &= ~(BCM2835_AUX_SPI_CNTL0_SPEED);
+	/* set the new speed */
+	bs->cntl[0] |= speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT;
+
+	spi_used_hz = clk_hz / (2 * (speed + 1));
+
+	/* 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;
+	bs->pending = 0;
+
+	/* Calculate the estimated time in us the transfer runs.  Note that
+	 * there are are 2 idle clocks cycles after each chunk getting
+	 * transferred - in our case the chunk size is 3 bytes, so we
+	 * approximate this by 9 cycles/byte.  This is used to find the number
+	 * of Hz per byte per polling limit.  E.g., we can transfer 1 byte in
+	 * 30 µs per 300,000 Hz of bus clock.
+	 */
+#define HZ_PER_BYTE ((9 * 1000000) / BCM2835_AUX_SPI_POLLING_LIMIT_US)
+	/* run in polling mode for short transfers */
+	if (tfr->len < spi_used_hz / HZ_PER_BYTE)
+		return bcm2835aux_spi_transfer_one_poll(master, spi, tfr);
+
+	/* run in interrupt mode for all others */
+	return bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+#undef HZ_PER_BYTE
+}
+
+static int bcm2835aux_spi_prepare_message(struct spi_master *master,
+					  struct spi_message *msg)
+{
+	struct spi_device *spi = msg->spi;
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bs->cntl[0] = BCM2835_AUX_SPI_CNTL0_ENABLE |
+		      BCM2835_AUX_SPI_CNTL0_VAR_WIDTH |
+		      BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
+	bs->cntl[1] = BCM2835_AUX_SPI_CNTL1_MSBF_IN;
+
+	/* handle all the modes */
+	if (spi->mode & SPI_CPOL) {
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPOL;
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_OUT_RISING;
+	} else {
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_IN_RISING;
+	}
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	return 0;
+}
+
+static int bcm2835aux_spi_unprepare_message(struct spi_master *master,
+					    struct spi_message *msg)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+
+	return 0;
+}
+
+static void bcm2835aux_spi_handle_err(struct spi_master *master,
+				      struct spi_message *msg)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+}
+
+static int bcm2835aux_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct bcm2835aux_spi *bs;
+	struct resource *res;
+	unsigned long clk_hz;
+	int err;
+
+	master = devm_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 = (SPI_CPOL | SPI_CS_HIGH | SPI_NO_CS);
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	/* even though the driver never officially supported native CS
+	 * allow a single native CS for legacy DT support purposes when
+	 * no cs-gpio is configured.
+	 * Known limitations for native cs are:
+	 * * multiple chip-selects: cs0-cs2 are all simultaniously asserted
+	 *     whenever there is a transfer -  this even includes SPI_NO_CS
+	 * * SPI_CS_HIGH: is ignores - cs are always asserted low
+	 * * cs_change: cs is deasserted after each spi_transfer
+	 * * cs_delay_usec: cs is always deasserted one SCK cycle after
+	 *     a spi_transfer
+	 */
+	master->num_chipselect = 1;
+	master->transfer_one = bcm2835aux_spi_transfer_one;
+	master->handle_err = bcm2835aux_spi_handle_err;
+	master->prepare_message = bcm2835aux_spi_prepare_message;
+	master->unprepare_message = bcm2835aux_spi_unprepare_message;
+	master->dev.of_node = pdev->dev.of_node;
+
+	bs = spi_master_get_devdata(master);
+
+	/* the main area */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bs->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(bs->regs))
+		return PTR_ERR(bs->regs);
+
+	bs->clk = devm_clk_get(&pdev->dev, NULL);
+	if ((!bs->clk) || (IS_ERR(bs->clk))) {
+		err = PTR_ERR(bs->clk);
+		dev_err(&pdev->dev, "could not get clk: %d\n", err);
+		return err;
+	}
+
+	bs->irq = platform_get_irq(pdev, 0);
+	if (bs->irq <= 0) {
+		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
+		return bs->irq ? bs->irq : -ENODEV;
+	}
+
+	/* this also enables the HW block */
+	err = clk_prepare_enable(bs->clk);
+	if (err) {
+		dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
+		return err;
+	}
+
+	/* just checking if the clock returns a sane value */
+	clk_hz = clk_get_rate(bs->clk);
+	if (!clk_hz) {
+		dev_err(&pdev->dev, "clock returns 0 Hz\n");
+		err = -ENODEV;
+		goto out_clk_disable;
+	}
+
+	/* reset SPI-HW block */
+	bcm2835aux_spi_reset_hw(bs);
+
+	err = devm_request_irq(&pdev->dev, bs->irq,
+			       bcm2835aux_spi_interrupt,
+			       IRQF_SHARED,
+			       dev_name(&pdev->dev), master);
+	if (err) {
+		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	err = spi_register_master(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);
+	return err;
+}
+
+static int bcm2835aux_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	spi_unregister_master(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+
+	/* disable the HW block by releasing the clock */
+	clk_disable_unprepare(bs->clk);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835aux_spi_match[] = {
+	{ .compatible = "brcm,bcm2835-aux-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bcm2835aux_spi_match);
+
+static struct platform_driver bcm2835aux_spi_driver = {
+	.driver		= {
+		.name		= "spi-bcm2835aux",
+		.of_match_table	= bcm2835aux_spi_match,
+	},
+	.probe		= bcm2835aux_spi_probe,
+	.remove		= bcm2835aux_spi_remove,
+};
+module_platform_driver(bcm2835aux_spi_driver);
+
+MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835 aux");
+MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
+MODULE_LICENSE("GPL v2");