--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+//
+// Apple SoC SPI device driver
+//
+// Copyright The Asahi Linux Contributors
+//
+// Based on spi-sifive.c, Copyright 2018 SiFive, Inc.
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/spi/spi.h>
+
+#define APPLE_SPI_CTRL 0x000
+#define APPLE_SPI_CTRL_RUN BIT(0)
+#define APPLE_SPI_CTRL_TX_RESET BIT(2)
+#define APPLE_SPI_CTRL_RX_RESET BIT(3)
+
+#define APPLE_SPI_CFG 0x004
+#define APPLE_SPI_CFG_CPHA BIT(1)
+#define APPLE_SPI_CFG_CPOL BIT(2)
+#define APPLE_SPI_CFG_MODE GENMASK(6, 5)
+#define APPLE_SPI_CFG_MODE_POLLED 0
+#define APPLE_SPI_CFG_MODE_IRQ 1
+#define APPLE_SPI_CFG_MODE_DMA 2
+#define APPLE_SPI_CFG_IE_RXCOMPLETE BIT(7)
+#define APPLE_SPI_CFG_IE_TXRXTHRESH BIT(8)
+#define APPLE_SPI_CFG_LSB_FIRST BIT(13)
+#define APPLE_SPI_CFG_WORD_SIZE GENMASK(16, 15)
+#define APPLE_SPI_CFG_WORD_SIZE_8B 0
+#define APPLE_SPI_CFG_WORD_SIZE_16B 1
+#define APPLE_SPI_CFG_WORD_SIZE_32B 2
+#define APPLE_SPI_CFG_FIFO_THRESH GENMASK(18, 17)
+#define APPLE_SPI_CFG_FIFO_THRESH_8B 0
+#define APPLE_SPI_CFG_FIFO_THRESH_4B 1
+#define APPLE_SPI_CFG_FIFO_THRESH_1B 2
+#define APPLE_SPI_CFG_IE_TXCOMPLETE BIT(21)
+
+#define APPLE_SPI_STATUS 0x008
+#define APPLE_SPI_STATUS_RXCOMPLETE BIT(0)
+#define APPLE_SPI_STATUS_TXRXTHRESH BIT(1)
+#define APPLE_SPI_STATUS_TXCOMPLETE BIT(2)
+
+#define APPLE_SPI_PIN 0x00c
+#define APPLE_SPI_PIN_KEEP_MOSI BIT(0)
+#define APPLE_SPI_PIN_CS BIT(1)
+
+#define APPLE_SPI_TXDATA 0x010
+#define APPLE_SPI_RXDATA 0x020
+#define APPLE_SPI_CLKDIV 0x030
+#define APPLE_SPI_CLKDIV_MAX 0x7ff
+#define APPLE_SPI_RXCNT 0x034
+#define APPLE_SPI_WORD_DELAY 0x038
+#define APPLE_SPI_TXCNT 0x04c
+
+#define APPLE_SPI_FIFOSTAT 0x10c
+#define APPLE_SPI_FIFOSTAT_TXFULL BIT(4)
+#define APPLE_SPI_FIFOSTAT_LEVEL_TX GENMASK(15, 8)
+#define APPLE_SPI_FIFOSTAT_RXEMPTY BIT(20)
+#define APPLE_SPI_FIFOSTAT_LEVEL_RX GENMASK(31, 24)
+
+#define APPLE_SPI_IE_XFER 0x130
+#define APPLE_SPI_IF_XFER 0x134
+#define APPLE_SPI_XFER_RXCOMPLETE BIT(0)
+#define APPLE_SPI_XFER_TXCOMPLETE BIT(1)
+
+#define APPLE_SPI_IE_FIFO 0x138
+#define APPLE_SPI_IF_FIFO 0x13c
+#define APPLE_SPI_FIFO_RXTHRESH BIT(4)
+#define APPLE_SPI_FIFO_TXTHRESH BIT(5)
+#define APPLE_SPI_FIFO_RXFULL BIT(8)
+#define APPLE_SPI_FIFO_TXEMPTY BIT(9)
+#define APPLE_SPI_FIFO_RXUNDERRUN BIT(16)
+#define APPLE_SPI_FIFO_TXOVERFLOW BIT(17)
+
+#define APPLE_SPI_SHIFTCFG 0x150
+#define APPLE_SPI_SHIFTCFG_CLK_ENABLE BIT(0)
+#define APPLE_SPI_SHIFTCFG_CS_ENABLE BIT(1)
+#define APPLE_SPI_SHIFTCFG_AND_CLK_DATA BIT(8)
+#define APPLE_SPI_SHIFTCFG_CS_AS_DATA BIT(9)
+#define APPLE_SPI_SHIFTCFG_TX_ENABLE BIT(10)
+#define APPLE_SPI_SHIFTCFG_RX_ENABLE BIT(11)
+#define APPLE_SPI_SHIFTCFG_BITS GENMASK(21, 16)
+#define APPLE_SPI_SHIFTCFG_OVERRIDE_CS BIT(24)
+
+#define APPLE_SPI_PINCFG 0x154
+#define APPLE_SPI_PINCFG_KEEP_CLK BIT(0)
+#define APPLE_SPI_PINCFG_KEEP_CS BIT(1)
+#define APPLE_SPI_PINCFG_KEEP_MOSI BIT(2)
+#define APPLE_SPI_PINCFG_CLK_IDLE_VAL BIT(8)
+#define APPLE_SPI_PINCFG_CS_IDLE_VAL BIT(9)
+#define APPLE_SPI_PINCFG_MOSI_IDLE_VAL BIT(10)
+
+#define APPLE_SPI_DELAY_PRE 0x160
+#define APPLE_SPI_DELAY_POST 0x168
+#define APPLE_SPI_DELAY_ENABLE BIT(0)
+#define APPLE_SPI_DELAY_NO_INTERBYTE BIT(1)
+#define APPLE_SPI_DELAY_SET_SCK BIT(4)
+#define APPLE_SPI_DELAY_SET_MOSI BIT(6)
+#define APPLE_SPI_DELAY_SCK_VAL BIT(8)
+#define APPLE_SPI_DELAY_MOSI_VAL BIT(12)
+
+#define APPLE_SPI_FIFO_DEPTH 16
+
+/*
+ * The slowest refclock available is 24MHz, the highest divider is 0x7ff,
+ * the largest word size is 32 bits, the FIFO depth is 16, the maximum
+ * intra-word delay is 0xffff refclocks. So the maximum time a transfer
+ * cycle can take is:
+ *
+ * (0x7ff * 32 + 0xffff) * 16 / 24e6 Hz ~= 87ms
+ *
+ * Double it and round it up to 200ms for good measure.
+ */
+#define APPLE_SPI_TIMEOUT_MS 200
+
+struct apple_spi {
+ void __iomem *regs; /* MMIO register address */
+ struct clk *clk; /* bus clock */
+ struct completion done; /* wake-up from interrupt */
+};
+
+static inline void reg_write(struct apple_spi *spi, int offset, u32 value)
+{
+ writel_relaxed(value, spi->regs + offset);
+}
+
+static inline u32 reg_read(struct apple_spi *spi, int offset)
+{
+ return readl_relaxed(spi->regs + offset);
+}
+
+static inline void reg_mask(struct apple_spi *spi, int offset, u32 clear, u32 set)
+{
+ u32 val = reg_read(spi, offset);
+
+ val &= ~clear;
+ val |= set;
+ reg_write(spi, offset, val);
+}
+
+static void apple_spi_init(struct apple_spi *spi)
+{
+ /* Set CS high (inactive) and disable override and auto-CS */
+ reg_write(spi, APPLE_SPI_PIN, APPLE_SPI_PIN_CS);
+ reg_mask(spi, APPLE_SPI_SHIFTCFG, APPLE_SPI_SHIFTCFG_OVERRIDE_CS, 0);
+ reg_mask(spi, APPLE_SPI_PINCFG, APPLE_SPI_PINCFG_CS_IDLE_VAL, APPLE_SPI_PINCFG_KEEP_CS);
+
+ /* Reset FIFOs */
+ reg_write(spi, APPLE_SPI_CTRL, APPLE_SPI_CTRL_RX_RESET | APPLE_SPI_CTRL_TX_RESET);
+
+ /* Configure defaults */
+ reg_write(spi, APPLE_SPI_CFG,
+ FIELD_PREP(APPLE_SPI_CFG_FIFO_THRESH, APPLE_SPI_CFG_FIFO_THRESH_8B) |
+ FIELD_PREP(APPLE_SPI_CFG_MODE, APPLE_SPI_CFG_MODE_IRQ) |
+ FIELD_PREP(APPLE_SPI_CFG_WORD_SIZE, APPLE_SPI_CFG_WORD_SIZE_8B));
+
+ /* Disable IRQs */
+ reg_write(spi, APPLE_SPI_IE_FIFO, 0);
+ reg_write(spi, APPLE_SPI_IE_XFER, 0);
+
+ /* Disable delays */
+ reg_write(spi, APPLE_SPI_DELAY_PRE, 0);
+ reg_write(spi, APPLE_SPI_DELAY_POST, 0);
+}
+
+static int apple_spi_prepare_message(struct spi_controller *ctlr, struct spi_message *msg)
+{
+ struct apple_spi *spi = spi_controller_get_devdata(ctlr);
+ struct spi_device *device = msg->spi;
+
+ u32 cfg = ((device->mode & SPI_CPHA ? APPLE_SPI_CFG_CPHA : 0) |
+ (device->mode & SPI_CPOL ? APPLE_SPI_CFG_CPOL : 0) |
+ (device->mode & SPI_LSB_FIRST ? APPLE_SPI_CFG_LSB_FIRST : 0));
+
+ /* Update core config */
+ reg_mask(spi, APPLE_SPI_CFG,
+ APPLE_SPI_CFG_CPHA | APPLE_SPI_CFG_CPOL | APPLE_SPI_CFG_LSB_FIRST, cfg);
+
+ return 0;
+}
+
+static void apple_spi_set_cs(struct spi_device *device, bool is_high)
+{
+ struct apple_spi *spi = spi_controller_get_devdata(device->controller);
+
+ reg_mask(spi, APPLE_SPI_PIN, APPLE_SPI_PIN_CS, is_high ? APPLE_SPI_PIN_CS : 0);
+}
+
+static bool apple_spi_prep_transfer(struct apple_spi *spi, struct spi_transfer *t)
+{
+ u32 cr, fifo_threshold;
+
+ /* Calculate and program the clock rate */
+ cr = DIV_ROUND_UP(clk_get_rate(spi->clk), t->speed_hz);
+ reg_write(spi, APPLE_SPI_CLKDIV, min_t(u32, cr, APPLE_SPI_CLKDIV_MAX));
+
+ /* Update bits per word */
+ reg_mask(spi, APPLE_SPI_SHIFTCFG, APPLE_SPI_SHIFTCFG_BITS,
+ FIELD_PREP(APPLE_SPI_SHIFTCFG_BITS, t->bits_per_word));
+
+ /* We will want to poll if the time we need to wait is
+ * less than the context switching time.
+ * Let's call that threshold 5us. The operation will take:
+ * bits_per_word * fifo_threshold / hz <= 5 * 10^-6
+ * 200000 * bits_per_word * fifo_threshold <= hz
+ */
+ fifo_threshold = APPLE_SPI_FIFO_DEPTH / 2;
+ return (200000 * t->bits_per_word * fifo_threshold) <= t->speed_hz;
+}
+
+static irqreturn_t apple_spi_irq(int irq, void *dev_id)
+{
+ struct apple_spi *spi = dev_id;
+ u32 fifo = reg_read(spi, APPLE_SPI_IF_FIFO) & reg_read(spi, APPLE_SPI_IE_FIFO);
+ u32 xfer = reg_read(spi, APPLE_SPI_IF_XFER) & reg_read(spi, APPLE_SPI_IE_XFER);
+
+ if (fifo || xfer) {
+ /* Disable interrupts until next transfer */
+ reg_write(spi, APPLE_SPI_IE_XFER, 0);
+ reg_write(spi, APPLE_SPI_IE_FIFO, 0);
+ complete(&spi->done);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static int apple_spi_wait(struct apple_spi *spi, u32 fifo_bit, u32 xfer_bit, int poll)
+{
+ int ret = 0;
+
+ if (poll) {
+ u32 fifo, xfer;
+ unsigned long timeout = jiffies + APPLE_SPI_TIMEOUT_MS * HZ / 1000;
+
+ do {
+ fifo = reg_read(spi, APPLE_SPI_IF_FIFO);
+ xfer = reg_read(spi, APPLE_SPI_IF_XFER);
+ if (time_after(jiffies, timeout)) {
+ ret = -ETIMEDOUT;
+ break;
+ }
+ } while (!((fifo & fifo_bit) || (xfer & xfer_bit)));
+ } else {
+ reinit_completion(&spi->done);
+ reg_write(spi, APPLE_SPI_IE_XFER, xfer_bit);
+ reg_write(spi, APPLE_SPI_IE_FIFO, fifo_bit);
+
+ if (!wait_for_completion_timeout(&spi->done,
+ msecs_to_jiffies(APPLE_SPI_TIMEOUT_MS)))
+ ret = -ETIMEDOUT;
+
+ reg_write(spi, APPLE_SPI_IE_XFER, 0);
+ reg_write(spi, APPLE_SPI_IE_FIFO, 0);
+ }
+
+ return ret;
+}
+
+static void apple_spi_tx(struct apple_spi *spi, const void **tx_ptr, u32 *left,
+ unsigned int bytes_per_word)
+{
+ u32 inuse, words, wrote;
+
+ if (!*tx_ptr)
+ return;
+
+ inuse = FIELD_GET(APPLE_SPI_FIFOSTAT_LEVEL_TX, reg_read(spi, APPLE_SPI_FIFOSTAT));
+ words = wrote = min_t(u32, *left, APPLE_SPI_FIFO_DEPTH - inuse);
+
+ if (!words)
+ return;
+
+ *left -= words;
+
+ switch (bytes_per_word) {
+ case 1: {
+ const u8 *p = *tx_ptr;
+
+ while (words--)
+ reg_write(spi, APPLE_SPI_TXDATA, *p++);
+ break;
+ }
+ case 2: {
+ const u16 *p = *tx_ptr;
+
+ while (words--)
+ reg_write(spi, APPLE_SPI_TXDATA, *p++);
+ break;
+ }
+ case 4: {
+ const u32 *p = *tx_ptr;
+
+ while (words--)
+ reg_write(spi, APPLE_SPI_TXDATA, *p++);
+ break;
+ }
+ default:
+ WARN_ON(1);
+ }
+
+ *tx_ptr = ((u8 *)*tx_ptr) + bytes_per_word * wrote;
+}
+
+static void apple_spi_rx(struct apple_spi *spi, void **rx_ptr, u32 *left,
+ unsigned int bytes_per_word)
+{
+ u32 words, read;
+
+ if (!*rx_ptr)
+ return;
+
+ words = read = FIELD_GET(APPLE_SPI_FIFOSTAT_LEVEL_RX, reg_read(spi, APPLE_SPI_FIFOSTAT));
+ WARN_ON(words > *left);
+
+ if (!words)
+ return;
+
+ *left -= min_t(u32, *left, words);
+
+ switch (bytes_per_word) {
+ case 1: {
+ u8 *p = *rx_ptr;
+
+ while (words--)
+ *p++ = reg_read(spi, APPLE_SPI_RXDATA);
+ break;
+ }
+ case 2: {
+ u16 *p = *rx_ptr;
+
+ while (words--)
+ *p++ = reg_read(spi, APPLE_SPI_RXDATA);
+ break;
+ }
+ case 4: {
+ u32 *p = *rx_ptr;
+
+ while (words--)
+ *p++ = reg_read(spi, APPLE_SPI_RXDATA);
+ break;
+ }
+ default:
+ WARN_ON(1);
+ }
+
+ *rx_ptr = ((u8 *)*rx_ptr) + bytes_per_word * read;
+}
+
+static int apple_spi_transfer_one(struct spi_controller *ctlr, struct spi_device *device,
+ struct spi_transfer *t)
+{
+ struct apple_spi *spi = spi_controller_get_devdata(ctlr);
+ bool poll = apple_spi_prep_transfer(spi, t);
+ const void *tx_ptr = t->tx_buf;
+ void *rx_ptr = t->rx_buf;
+ unsigned int bytes_per_word;
+ u32 words, remaining_tx, remaining_rx;
+ u32 xfer_flags = 0;
+ u32 fifo_flags;
+ int retries = 100;
+ int ret = 0;
+
+ if (t->bits_per_word > 16)
+ bytes_per_word = 4;
+ else if (t->bits_per_word > 8)
+ bytes_per_word = 2;
+ else
+ bytes_per_word = 1;
+
+ words = t->len / bytes_per_word;
+ remaining_tx = tx_ptr ? words : 0;
+ remaining_rx = rx_ptr ? words : 0;
+
+ /* Reset FIFOs */
+ reg_write(spi, APPLE_SPI_CTRL, APPLE_SPI_CTRL_RX_RESET | APPLE_SPI_CTRL_TX_RESET);
+
+ /* Clear IRQ flags */
+ reg_write(spi, APPLE_SPI_IF_XFER, ~0);
+ reg_write(spi, APPLE_SPI_IF_FIFO, ~0);
+
+ /* Determine transfer completion flags we wait for */
+ if (tx_ptr)
+ xfer_flags |= APPLE_SPI_XFER_TXCOMPLETE;
+ if (rx_ptr)
+ xfer_flags |= APPLE_SPI_XFER_RXCOMPLETE;
+
+ /* Set transfer length */
+ reg_write(spi, APPLE_SPI_TXCNT, remaining_tx);
+ reg_write(spi, APPLE_SPI_RXCNT, remaining_rx);
+
+ /* Prime transmit FIFO */
+ apple_spi_tx(spi, &tx_ptr, &remaining_tx, bytes_per_word);
+
+ /* Start transfer */
+ reg_write(spi, APPLE_SPI_CTRL, APPLE_SPI_CTRL_RUN);
+
+ /* TX again since a few words get popped off immediately */
+ apple_spi_tx(spi, &tx_ptr, &remaining_tx, bytes_per_word);
+
+ while (xfer_flags) {
+ fifo_flags = 0;
+
+ if (remaining_tx)
+ fifo_flags |= APPLE_SPI_FIFO_TXTHRESH;
+ if (remaining_rx)
+ fifo_flags |= APPLE_SPI_FIFO_RXTHRESH;
+
+ /* Wait for anything to happen */
+ ret = apple_spi_wait(spi, fifo_flags, xfer_flags, poll);
+ if (ret) {
+ dev_err(&ctlr->dev, "transfer timed out (remaining %d tx, %d rx)\n",
+ remaining_tx, remaining_rx);
+ goto err;
+ }
+
+ /* Stop waiting on transfer halves once they complete */
+ xfer_flags &= ~reg_read(spi, APPLE_SPI_IF_XFER);
+
+ /* Transmit and receive everything we can */
+ apple_spi_tx(spi, &tx_ptr, &remaining_tx, bytes_per_word);
+ apple_spi_rx(spi, &rx_ptr, &remaining_rx, bytes_per_word);
+ }
+
+ /*
+ * Sometimes the transfer completes before the last word is in the RX FIFO.
+ * Normally one retry is all it takes to get the last word out.
+ */
+ while (remaining_rx && retries--)
+ apple_spi_rx(spi, &rx_ptr, &remaining_rx, bytes_per_word);
+
+ if (remaining_tx)
+ dev_err(&ctlr->dev, "transfer completed with %d words left to transmit\n",
+ remaining_tx);
+ if (remaining_rx)
+ dev_err(&ctlr->dev, "transfer completed with %d words left to receive\n",
+ remaining_rx);
+
+err:
+ fifo_flags = reg_read(spi, APPLE_SPI_IF_FIFO);
+ WARN_ON(fifo_flags & APPLE_SPI_FIFO_TXOVERFLOW);
+ WARN_ON(fifo_flags & APPLE_SPI_FIFO_RXUNDERRUN);
+
+ /* Stop transfer */
+ reg_write(spi, APPLE_SPI_CTRL, 0);
+
+ return ret;
+}
+
+static int apple_spi_probe(struct platform_device *pdev)
+{
+ struct apple_spi *spi;
+ int ret, irq;
+ struct spi_controller *ctlr;
+
+ ctlr = devm_spi_alloc_host(&pdev->dev, sizeof(struct apple_spi));
+ if (!ctlr)
+ return -ENOMEM;
+
+ spi = spi_controller_get_devdata(ctlr);
+ init_completion(&spi->done);
+
+ spi->regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(spi->regs))
+ return PTR_ERR(spi->regs);
+
+ spi->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+ if (IS_ERR(spi->clk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(spi->clk),
+ "Unable to find or enable bus clock\n");
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ ret = devm_request_irq(&pdev->dev, irq, apple_spi_irq, 0,
+ dev_name(&pdev->dev), spi);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret, "Unable to bind to interrupt\n");
+
+ ctlr->dev.of_node = pdev->dev.of_node;
+ ctlr->bus_num = pdev->id;
+ ctlr->num_chipselect = 1;
+ ctlr->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
+ ctlr->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
+ ctlr->prepare_message = apple_spi_prepare_message;
+ ctlr->set_cs = apple_spi_set_cs;
+ ctlr->transfer_one = apple_spi_transfer_one;
+ ctlr->auto_runtime_pm = true;
+
+ pm_runtime_set_active(&pdev->dev);
+ ret = devm_pm_runtime_enable(&pdev->dev);
+ if (ret < 0)
+ return ret;
+
+ apple_spi_init(spi);
+
+ ret = devm_spi_register_controller(&pdev->dev, ctlr);
+ if (ret < 0)
+ return dev_err_probe(&pdev->dev, ret, "devm_spi_register_controller failed\n");
+
+ return 0;
+}
+
+static const struct of_device_id apple_spi_of_match[] = {
+ { .compatible = "apple,spi", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, apple_spi_of_match);
+
+static struct platform_driver apple_spi_driver = {
+ .probe = apple_spi_probe,
+ .driver = {
+ .name = "apple-spi",
+ .owner = THIS_MODULE,
+ .of_match_table = apple_spi_of_match,
+ },
+};
+module_platform_driver(apple_spi_driver);
+
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_DESCRIPTION("Apple SoC SPI driver");
+MODULE_LICENSE("GPL");
projects / thirdparty / kernel / linux.git / commitdiff
