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SubjectRe: [PATCH 3/3] spi: apple: Add driver for Apple SPI controller


On Sun, Dec 12, 2021, at 04:47, Hector Martin wrote:
> This SPI controller is present in Apple SoCs such as the M1 (t8103) and
> M1 Pro/Max (t600x). It is a relatively straightforward design with two
> 16-entry FIFOs, arbitrary transfer sizes (up to 2**32 - 1) and fully
> configurable word size up to 32 bits. It supports one hardware CS line
> which can also be driven via the pinctrl/GPIO driver instead, if
> desired. TX and RX can be independently enabled.
>
> There are a surprising number of knobs for tweaking details of the
> transfer, most of which we do not use right now. Hardware CS control
> is available, but we haven't found a way to make it stay low across
> multiple logical transfers, so we just use software CS control for now.
>
> There is also a shared DMA offload coprocessor that can be used to handle
> larger transfers without requiring an IRQ every 8-16 words, but that
> feature depends on a bunch of scaffolding that isn't ready to be
> upstreamed yet, so leave it for later.
>
> The hardware shares some register bit definitions with spi-s3c24xx which
> suggests it has a shared legacy with Samsung SoCs, but it is too
> different to warrant sharing a driver.
>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---

Looks good to me, I just have a few nits below.

> drivers/spi/Kconfig | 8 +
> drivers/spi/Makefile | 1 +
> drivers/spi/spi-apple.c | 566 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 575 insertions(+)
> create mode 100644 drivers/spi/spi-apple.c
>
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index b2a8821971e1..d4369c73d4ea 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -79,6 +79,14 @@ config SPI_ALTERA_DFL
> Altera SPI master controller. The SPI master is connected
> to a SPI slave to Avalon bridge in a Intel MAX BMC.
>
> +config SPI_APPLE
> + tristate "Apple SoC SPI Controller platform driver"
> + depends on ARCH_APPLE || COMPILE_TEST
> + help
> + This enables support for the SPI controller present on
> + many Apple SoCs, including the t8103 (M1) and t600x
> + (M1 Pro/Max).
> +
> config SPI_AR934X
> tristate "Qualcomm Atheros AR934X/QCA95XX SPI controller driver"
> depends on ATH79 || COMPILE_TEST
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index dd7393a6046f..35624999d6aa 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_SPI_LOOPBACK_TEST) +=
> spi-loopback-test.o
> obj-$(CONFIG_SPI_ALTERA) += spi-altera-platform.o
> obj-$(CONFIG_SPI_ALTERA_CORE) += spi-altera-core.o
> obj-$(CONFIG_SPI_ALTERA_DFL) += spi-altera-dfl.o
> +obj-$(CONFIG_SPI_APPLE) += spi-apple.o
> obj-$(CONFIG_SPI_AR934X) += spi-ar934x.o
> obj-$(CONFIG_SPI_ARMADA_3700) += spi-armada-3700.o
> obj-$(CONFIG_SPI_ATMEL) += spi-atmel.o
> diff --git a/drivers/spi/spi-apple.c b/drivers/spi/spi-apple.c
> new file mode 100644
> index 000000000000..67d93048bb58
> --- /dev/null
> +++ b/drivers/spi/spi-apple.c
> @@ -0,0 +1,566 @@
> +// 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/bits.h> for GENMASK even though it's probably
pulled in by one of the #includes below

> +#include <linux/bitfield.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_DRIVER_NAME "apple_spi"
> +
> +#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;
> +
> + /* 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
> + */
> + return 200000 * t->bits_per_word * APPLE_SPI_FIFO_DEPTH / 2 <=
> t->speed_hz;

Nice :-)

> +}
> +
> +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 = t->bits_per_word > 16 ? 4 :
> t->bits_per_word > 8 ? 2 : 1;
> + u32 words = t->len / bytes_per_word;
> + u32 remaining_tx = tx_ptr ? words : 0;
> + u32 remaining_rx = rx_ptr ? words : 0;
> + u32 xfer_flags = 0;
> + u32 fifo_flags;
> + int retries = 100;
> + int ret = 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) {
> + u32 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 = spi_alloc_master(&pdev->dev, sizeof(struct apple_spi));

devm_spi_alloc_master and then you can get rid of the spi_controller_put
error path.

> + if (!ctlr) {
> + dev_err(&pdev->dev, "out of memory\n");
> + return -ENOMEM;
> + }
> +
> + 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)) {
> + ret = PTR_ERR(spi->regs);
> + goto put_ctlr;
> + }
> +
> + spi->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(spi->clk)) {
> + dev_err(&pdev->dev, "Unable to find bus clock\n");
> + ret = PTR_ERR(spi->clk);
> + goto put_ctlr;
> + }

dev_err_probe can be used here in case devm_clk_get returns -EPROBE_DEFER.

> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0) {
> + ret = irq;
> + goto put_ctlr;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, irq, apple_spi_irq, 0,
> + dev_name(&pdev->dev), spi);
> + if (ret) {
> + dev_err(&pdev->dev, "Unable to bind to interrupt\n");
> + goto put_ctlr;
> + }
> +
> + ret = clk_prepare_enable(spi->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "Unable to enable bus clock\n");
> + goto put_ctlr;
> + }

Unfortunately there's no devm_clk_prepare_enable but you could use
devm_add_action_or_reset like almost all watchdog drivers as well.

> +
> + 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);
> + pm_runtime_enable(&pdev->dev);

You could also use devm_pm_runtime_enable here and then everything
should be devres managed.

> +
> + pdev->dev.dma_mask = NULL;
> +
> + apple_spi_init(spi);
> +
> + ret = devm_spi_register_controller(&pdev->dev, ctlr);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "spi_register_ctlr failed\n");
> + goto disable_pm;
> + }
> +
> + return 0;
> +
> +disable_pm:
> + pm_runtime_disable(&pdev->dev);
> + clk_disable_unprepare(spi->clk);
> +put_ctlr:
> + spi_controller_put(ctlr);
> +
> + return ret;
> +}
> +
> +static int apple_spi_remove(struct platform_device *pdev)
> +{
> + struct spi_controller *ctlr = platform_get_drvdata(pdev);
> + struct apple_spi *spi = spi_controller_get_devdata(ctlr);
> +
> + pm_runtime_disable(&pdev->dev);
> +
> + /* Disable all the interrupts just in case */
> + reg_write(spi, APPLE_SPI_IE_FIFO, 0);
> + reg_write(spi, APPLE_SPI_IE_XFER, 0);
> +
> + clk_disable_unprepare(spi->clk);
> +
> + 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,
> + .remove = apple_spi_remove,
> + .driver = {
> + .name = APPLE_SPI_DRIVER_NAME,
> + .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");
> --
> 2.33.0

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