--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff