diff options
Diffstat (limited to 'drivers/spi/spi-apple.c')
| -rw-r--r-- | drivers/spi/spi-apple.c | 544 |
1 files changed, 544 insertions, 0 deletions
diff --git a/drivers/spi/spi-apple.c b/drivers/spi/spi-apple.c new file mode 100644 index 000000000000..c483ad3f69ef --- /dev/null +++ b/drivers/spi/spi-apple.c @@ -0,0 +1,544 @@ +// 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/module.h> +#include <linux/interrupt.h> +#include <linux/io.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 void apple_spi_clk_disable_unprepare(void *data) +{ + clk_disable_unprepare(data); +} + +static int apple_spi_probe(struct platform_device *pdev) +{ + struct apple_spi *spi; + int ret, irq; + struct spi_controller *ctlr; + + ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(struct apple_spi)); + if (!ctlr) + return dev_err_probe(&pdev->dev, -ENOMEM, "out of memory\n"); + + spi = spi_controller_get_devdata(ctlr); + init_completion(&spi->done); + platform_set_drvdata(pdev, ctlr); + + spi->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(spi->regs)) + return PTR_ERR(spi->regs); + + spi->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(spi->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(spi->clk), "Unable to find 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"); + + ret = clk_prepare_enable(spi->clk); + if (ret) + return dev_err_probe(&pdev->dev, ret, "Unable to enable bus clock\n"); + + ret = devm_add_action_or_reset(&pdev->dev, apple_spi_clk_disable_unprepare, spi->clk); + if (ret) + return ret; + + 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->flags = 0; + 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); + devm_pm_runtime_enable(&pdev->dev); + + 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"); |