--- /dev/null
+/*
+ * Driver for Amlogic Meson SPI communication controller (SPICC)
+ *
+ * Copyright (C) BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/reset.h>
+#include <linux/gpio.h>
+
+/*
+ * The Meson SPICC controller could support DMA based transfers, but is not
+ * implemented by the vendor code, and while having the registers documentation
+ * it has never worked on the GXL Hardware.
+ * The PIO mode is the only mode implemented, and due to badly designed HW :
+ * - all transfers are cutted in 16 words burst because the FIFO hangs on
+ * TX underflow, and there is no TX "Half-Empty" interrupt, so we go by
+ * FIFO max size chunk only
+ * - CS management is dumb, and goes UP between every burst, so is really a
+ * "Data Valid" signal than a Chip Select, GPIO link should be used instead
+ * to have a CS go down over the full transfer
+ */
+
+#define SPICC_MAX_FREQ 30000000
+#define SPICC_MAX_BURST 128
+
+/* Register Map */
+#define SPICC_RXDATA 0x00
+
+#define SPICC_TXDATA 0x04
+
+#define SPICC_CONREG 0x08
+#define SPICC_ENABLE BIT(0)
+#define SPICC_MODE_MASTER BIT(1)
+#define SPICC_XCH BIT(2)
+#define SPICC_SMC BIT(3)
+#define SPICC_POL BIT(4)
+#define SPICC_PHA BIT(5)
+#define SPICC_SSCTL BIT(6)
+#define SPICC_SSPOL BIT(7)
+#define SPICC_DRCTL_MASK GENMASK(9, 8)
+#define SPICC_DRCTL_IGNORE 0
+#define SPICC_DRCTL_FALLING 1
+#define SPICC_DRCTL_LOWLEVEL 2
+#define SPICC_CS_MASK GENMASK(13, 12)
+#define SPICC_DATARATE_MASK GENMASK(18, 16)
+#define SPICC_DATARATE_DIV4 0
+#define SPICC_DATARATE_DIV8 1
+#define SPICC_DATARATE_DIV16 2
+#define SPICC_DATARATE_DIV32 3
+#define SPICC_BITLENGTH_MASK GENMASK(24, 19)
+#define SPICC_BURSTLENGTH_MASK GENMASK(31, 25)
+
+#define SPICC_INTREG 0x0c
+#define SPICC_TE_EN BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH_EN BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF_EN BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR_EN BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH_EN BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF_EN BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO_EN BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC_EN BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_DMAREG 0x10
+#define SPICC_DMA_ENABLE BIT(0)
+#define SPICC_TXFIFO_THRESHOLD_MASK GENMASK(5, 1)
+#define SPICC_RXFIFO_THRESHOLD_MASK GENMASK(10, 6)
+#define SPICC_READ_BURST_MASK GENMASK(14, 11)
+#define SPICC_WRITE_BURST_MASK GENMASK(18, 15)
+#define SPICC_DMA_URGENT BIT(19)
+#define SPICC_DMA_THREADID_MASK GENMASK(25, 20)
+#define SPICC_DMA_BURSTNUM_MASK GENMASK(31, 26)
+
+#define SPICC_STATREG 0x14
+#define SPICC_TE BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_PERIODREG 0x18
+#define SPICC_PERIOD GENMASK(14, 0) /* Wait cycles */
+
+#define SPICC_TESTREG 0x1c
+#define SPICC_TXCNT_MASK GENMASK(4, 0) /* TX FIFO Counter */
+#define SPICC_RXCNT_MASK GENMASK(9, 5) /* RX FIFO Counter */
+#define SPICC_SMSTATUS_MASK GENMASK(12, 10) /* State Machine Status */
+#define SPICC_LBC_RO BIT(13) /* Loop Back Control Read-Only */
+#define SPICC_LBC_W1 BIT(14) /* Loop Back Control Write-Only */
+#define SPICC_SWAP_RO BIT(14) /* RX FIFO Data Swap Read-Only */
+#define SPICC_SWAP_W1 BIT(15) /* RX FIFO Data Swap Write-Only */
+#define SPICC_DLYCTL_RO_MASK GENMASK(20, 15) /* Delay Control Read-Only */
+#define SPICC_DLYCTL_W1_MASK GENMASK(21, 16) /* Delay Control Write-Only */
+#define SPICC_FIFORST_RO_MASK GENMASK(22, 21) /* FIFO Softreset Read-Only */
+#define SPICC_FIFORST_W1_MASK GENMASK(23, 22) /* FIFO Softreset Write-Only */
+
+#define SPICC_DRADDR 0x20 /* Read Address of DMA */
+
+#define SPICC_DWADDR 0x24 /* Write Address of DMA */
+
+#define writel_bits_relaxed(mask, val, addr) \
+ writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
+
+#define SPICC_BURST_MAX 16
+#define SPICC_FIFO_HALF 10
+
+struct meson_spicc_device {
+ struct spi_master *master;
+ struct platform_device *pdev;
+ void __iomem *base;
+ struct clk *core;
+ struct spi_message *message;
+ struct spi_transfer *xfer;
+ u8 *tx_buf;
+ u8 *rx_buf;
+ unsigned int bytes_per_word;
+ unsigned long tx_remain;
+ unsigned long txb_remain;
+ unsigned long rx_remain;
+ unsigned long rxb_remain;
+ unsigned long xfer_remain;
+ bool is_burst_end;
+ bool is_last_burst;
+};
+
+static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
+{
+ return !!FIELD_GET(SPICC_TF,
+ readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc)
+{
+ return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF_EN,
+ readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline u32 meson_spicc_pull_data(struct meson_spicc_device *spicc)
+{
+ unsigned int bytes = spicc->bytes_per_word;
+ unsigned int byte_shift = 0;
+ u32 data = 0;
+ u8 byte;
+
+ while (bytes--) {
+ byte = *spicc->tx_buf++;
+ data |= (byte & 0xff) << byte_shift;
+ byte_shift += 8;
+ }
+
+ spicc->tx_remain--;
+ return data;
+}
+
+static inline void meson_spicc_push_data(struct meson_spicc_device *spicc,
+ u32 data)
+{
+ unsigned int bytes = spicc->bytes_per_word;
+ unsigned int byte_shift = 0;
+ u8 byte;
+
+ while (bytes--) {
+ byte = (data >> byte_shift) & 0xff;
+ *spicc->rx_buf++ = byte;
+ byte_shift += 8;
+ }
+
+ spicc->rx_remain--;
+}
+
+static inline void meson_spicc_rx(struct meson_spicc_device *spicc)
+{
+ /* Empty RX FIFO */
+ while (spicc->rx_remain &&
+ meson_spicc_rxready(spicc))
+ meson_spicc_push_data(spicc,
+ readl_relaxed(spicc->base + SPICC_RXDATA));
+}
+
+static inline void meson_spicc_tx(struct meson_spicc_device *spicc)
+{
+ /* Fill Up TX FIFO */
+ while (spicc->tx_remain &&
+ !meson_spicc_txfull(spicc))
+ writel_relaxed(meson_spicc_pull_data(spicc),
+ spicc->base + SPICC_TXDATA);
+}
+
+static inline u32 meson_spicc_setup_rx_irq(struct meson_spicc_device *spicc,
+ u32 irq_ctrl)
+{
+ if (spicc->rx_remain > SPICC_FIFO_HALF)
+ irq_ctrl |= SPICC_RH_EN;
+ else
+ irq_ctrl |= SPICC_RR_EN;
+
+ return irq_ctrl;
+}
+
+static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc,
+ unsigned int burst_len)
+{
+ /* Setup Xfer variables */
+ spicc->tx_remain = burst_len;
+ spicc->rx_remain = burst_len;
+ spicc->xfer_remain -= burst_len * spicc->bytes_per_word;
+ spicc->is_burst_end = false;
+ if (burst_len < SPICC_BURST_MAX || !spicc->xfer_remain)
+ spicc->is_last_burst = true;
+ else
+ spicc->is_last_burst = false;
+
+ /* Setup burst length */
+ writel_bits_relaxed(SPICC_BURSTLENGTH_MASK,
+ FIELD_PREP(SPICC_BURSTLENGTH_MASK,
+ burst_len),
+ spicc->base + SPICC_CONREG);
+
+ /* Fill TX FIFO */
+ meson_spicc_tx(spicc);
+}
+
+static irqreturn_t meson_spicc_irq(int irq, void *data)
+{
+ struct meson_spicc_device *spicc = (void *) data;
+ u32 ctrl = readl_relaxed(spicc->base + SPICC_INTREG);
+ u32 stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+
+ ctrl &= ~(SPICC_RH_EN | SPICC_RR_EN);
+
+ /* Empty RX FIFO */
+ meson_spicc_rx(spicc);
+
+ /* Enable TC interrupt since we transferred everything */
+ if (!spicc->tx_remain && !spicc->rx_remain) {
+ spicc->is_burst_end = true;
+
+ /* Enable TC interrupt */
+ ctrl |= SPICC_TC_EN;
+
+ /* Reload IRQ status */
+ stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+ }
+
+ /* Check transfer complete */
+ if ((stat & SPICC_TC) && spicc->is_burst_end) {
+ unsigned int burst_len;
+
+ /* Clear TC bit */
+ writel_relaxed(SPICC_TC, spicc->base + SPICC_STATREG);
+
+ /* Disable TC interrupt */
+ ctrl &= ~SPICC_TC_EN;
+
+ if (spicc->is_last_burst) {
+ /* Disable all IRQs */
+ writel(0, spicc->base + SPICC_INTREG);
+
+ spi_finalize_current_transfer(spicc->master);
+
+ return IRQ_HANDLED;
+ }
+
+ burst_len = min_t(unsigned int,
+ spicc->xfer_remain / spicc->bytes_per_word,
+ SPICC_BURST_MAX);
+
+ /* Setup burst */
+ meson_spicc_setup_burst(spicc, burst_len);
+
+ /* Restart burst */
+ writel_bits_relaxed(SPICC_XCH, SPICC_XCH,
+ spicc->base + SPICC_CONREG);
+ }
+
+ /* Setup RX interrupt trigger */
+ ctrl = meson_spicc_setup_rx_irq(spicc, ctrl);
+
+ /* Reconfigure interrupts */
+ writel(ctrl, spicc->base + SPICC_INTREG);
+
+ return IRQ_HANDLED;
+}
+
+static u32 meson_spicc_setup_speed(struct meson_spicc_device *spicc, u32 conf,
+ u32 speed)
+{
+ unsigned long parent, value;
+ unsigned int i, div;
+
+ parent = clk_get_rate(spicc->core);
+
+ /* Find closest inferior/equal possible speed */
+ for (i = 0 ; i < 7 ; ++i) {
+ /* 2^(data_rate+2) */
+ value = parent >> (i + 2);
+
+ if (value <= speed)
+ break;
+ }
+
+ /* If provided speed it lower than max divider, use max divider */
+ if (i > 7) {
+ div = 7;
+ dev_warn_once(&spicc->pdev->dev, "unable to get close to speed %u\n",
+ speed);
+ } else
+ div = i;
+
+ dev_dbg(&spicc->pdev->dev, "parent %lu, speed %u -> %lu (%u)\n",
+ parent, speed, value, div);
+
+ conf &= ~SPICC_DATARATE_MASK;
+ conf |= FIELD_PREP(SPICC_DATARATE_MASK, div);
+
+ return conf;
+}
+
+static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
+ struct spi_transfer *xfer)
+{
+ u32 conf, conf_orig;
+
+ /* Read original configuration */
+ conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG);
+
+ /* Select closest divider */
+ conf = meson_spicc_setup_speed(spicc, conf, xfer->speed_hz);
+
+ /* Setup word width */
+ conf &= ~SPICC_BITLENGTH_MASK;
+ conf |= FIELD_PREP(SPICC_BITLENGTH_MASK,
+ (spicc->bytes_per_word << 3) - 1);
+
+ /* Ignore if unchanged */
+ if (conf != conf_orig)
+ writel_relaxed(conf, spicc->base + SPICC_CONREG);
+}
+
+static int meson_spicc_transfer_one(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *xfer)
+{
+ struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+ unsigned int burst_len;
+ u32 irq = 0;
+
+ /* Store current transfer */
+ spicc->xfer = xfer;
+
+ /* Setup transfer parameters */
+ spicc->tx_buf = (u8 *)xfer->tx_buf;
+ spicc->rx_buf = (u8 *)xfer->rx_buf;
+ spicc->xfer_remain = xfer->len;
+
+ /* Pre-calculate word size */
+ spicc->bytes_per_word =
+ DIV_ROUND_UP(spicc->xfer->bits_per_word, 8);
+
+ /* Setup transfer parameters */
+ meson_spicc_setup_xfer(spicc, xfer);
+
+ burst_len = min_t(unsigned int,
+ spicc->xfer_remain / spicc->bytes_per_word,
+ SPICC_BURST_MAX);
+
+ meson_spicc_setup_burst(spicc, burst_len);
+
+ irq = meson_spicc_setup_rx_irq(spicc, irq);
+
+ /* Start burst */
+ writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);
+
+ /* Enable interrupts */
+ writel_relaxed(irq, spicc->base + SPICC_INTREG);
+
+ return 1;
+}
+
+static int meson_spicc_prepare_message(struct spi_master *master,
+ struct spi_message *message)
+{
+ struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+ struct spi_device *spi = message->spi;
+ u32 conf = 0;
+
+ /* Store current message */
+ spicc->message = message;
+
+ /* Enable Master */
+ conf |= SPICC_ENABLE;
+ conf |= SPICC_MODE_MASTER;
+
+ /* SMC = 0 */
+
+ /* Setup transfer mode */
+ if (spi->mode & SPI_CPOL)
+ conf |= SPICC_POL;
+ else
+ conf &= ~SPICC_POL;
+
+ if (spi->mode & SPI_CPHA)
+ conf |= SPICC_PHA;
+ else
+ conf &= ~SPICC_PHA;
+
+ /* SSCTL = 0 */
+
+ if (spi->mode & SPI_CS_HIGH)
+ conf |= SPICC_SSPOL;
+ else
+ conf &= ~SPICC_SSPOL;
+
+ if (spi->mode & SPI_READY)
+ conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_LOWLEVEL);
+ else
+ conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_IGNORE);
+
+ /* Select CS */
+ conf |= FIELD_PREP(SPICC_CS_MASK, spi->chip_select);
+
+ /* Default Clock rate core/4 */
+
+ /* Default 8bit word */
+ conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1);
+
+ writel_relaxed(conf, spicc->base + SPICC_CONREG);
+
+ /* Setup no wait cycles by default */
+ writel_relaxed(0, spicc->base + SPICC_PERIODREG);
+
+ writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
+
+ return 0;
+}
+
+static int meson_spicc_unprepare_transfer(struct spi_master *master)
+{
+ struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+
+ /* Disable all IRQs */
+ writel(0, spicc->base + SPICC_INTREG);
+
+ /* Disable controller */
+ writel_bits_relaxed(SPICC_ENABLE, 0, spicc->base + SPICC_CONREG);
+
+ device_reset_optional(&spicc->pdev->dev);
+
+ return 0;
+}
+
+static int meson_spicc_setup(struct spi_device *spi)
+{
+ int ret = 0;
+
+ if (!spi->controller_state)
+ spi->controller_state = spi_master_get_devdata(spi->master);
+ else if (gpio_is_valid(spi->cs_gpio))
+ goto out_gpio;
+ else if (spi->cs_gpio == -ENOENT)
+ return 0;
+
+ if (gpio_is_valid(spi->cs_gpio)) {
+ ret = gpio_request(spi->cs_gpio, dev_name(&spi->dev));
+ if (ret) {
+ dev_err(&spi->dev, "failed to request cs gpio\n");
+ return ret;
+ }
+ }
+
+out_gpio:
+ ret = gpio_direction_output(spi->cs_gpio,
+ !(spi->mode & SPI_CS_HIGH));
+
+ return ret;
+}
+
+static void meson_spicc_cleanup(struct spi_device *spi)
+{
+ if (gpio_is_valid(spi->cs_gpio))
+ gpio_free(spi->cs_gpio);
+
+ spi->controller_state = NULL;
+}
+
+static int meson_spicc_probe(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct meson_spicc_device *spicc;
+ struct resource *res;
+ int ret, irq, rate;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*spicc));
+ if (!master) {
+ dev_err(&pdev->dev, "master allocation failed\n");
+ return -ENOMEM;
+ }
+ spicc = spi_master_get_devdata(master);
+ spicc->master = master;
+
+ spicc->pdev = pdev;
+ platform_set_drvdata(pdev, spicc);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ spicc->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(spicc->base)) {
+ dev_err(&pdev->dev, "io resource mapping failed\n");
+ ret = PTR_ERR(spicc->base);
+ goto out_master;
+ }
+
+ /* Disable all IRQs */
+ writel_relaxed(0, spicc->base + SPICC_INTREG);
+
+ irq = platform_get_irq(pdev, 0);
+ ret = devm_request_irq(&pdev->dev, irq, meson_spicc_irq,
+ 0, NULL, spicc);
+ if (ret) {
+ dev_err(&pdev->dev, "irq request failed\n");
+ goto out_master;
+ }
+
+ spicc->core = devm_clk_get(&pdev->dev, "core");
+ if (IS_ERR(spicc->core)) {
+ dev_err(&pdev->dev, "core clock request failed\n");
+ ret = PTR_ERR(spicc->core);
+ goto out_master;
+ }
+
+ ret = clk_prepare_enable(spicc->core);
+ if (ret) {
+ dev_err(&pdev->dev, "core clock enable failed\n");
+ goto out_master;
+ }
+ rate = clk_get_rate(spicc->core);
+
+ device_reset_optional(&pdev->dev);
+
+ master->num_chipselect = 4;
+ master->dev.of_node = pdev->dev.of_node;
+ master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH;
+ master->bits_per_word_mask = SPI_BPW_MASK(32) |
+ SPI_BPW_MASK(24) |
+ SPI_BPW_MASK(16) |
+ SPI_BPW_MASK(8);
+ master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX);
+ master->min_speed_hz = rate >> 9;
+ master->setup = meson_spicc_setup;
+ master->cleanup = meson_spicc_cleanup;
+ master->prepare_message = meson_spicc_prepare_message;
+ master->unprepare_transfer_hardware = meson_spicc_unprepare_transfer;
+ master->transfer_one = meson_spicc_transfer_one;
+
+ /* Setup max rate according to the Meson GX datasheet */
+ if ((rate >> 2) > SPICC_MAX_FREQ)
+ master->max_speed_hz = SPICC_MAX_FREQ;
+ else
+ master->max_speed_hz = rate >> 2;
+
+ ret = devm_spi_register_master(&pdev->dev, master);
+ if (!ret)
+ return 0;
+
+ dev_err(&pdev->dev, "spi master registration failed\n");
+
+out_master:
+ spi_master_put(master);
+
+ return ret;
+}
+
+static int meson_spicc_remove(struct platform_device *pdev)
+{
+ struct meson_spicc_device *spicc = platform_get_drvdata(pdev);
+
+ /* Disable SPI */
+ writel(0, spicc->base + SPICC_CONREG);
+
+ clk_disable_unprepare(spicc->core);
+
+ return 0;
+}
+
+static const struct of_device_id meson_spicc_of_match[] = {
+ { .compatible = "amlogic,meson-gx-spicc", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_spicc_of_match);
+
+static struct platform_driver meson_spicc_driver = {
+ .probe = meson_spicc_probe,
+ .remove = meson_spicc_remove,
+ .driver = {
+ .name = "meson-spicc",
+ .of_match_table = of_match_ptr(meson_spicc_of_match),
+ },
+};
+
+module_platform_driver(meson_spicc_driver);
+
+MODULE_DESCRIPTION("Meson SPI Communication Controller driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL");
git.samba.org / sfrench / cifs-2.6.git / commitdiff