--- /dev/null
+/*
+ * Freescale i.MX7ULP LPSPI driver
+ *
+ * Copyright 2016 Freescale Semiconductor, Inc.
+ *
+ * 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.
+ */
+#define DEBUG
+
+#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/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/types.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#define DRIVER_NAME "fsl_lpspi"
+
+/* i.MX7ULP LPSPI registers */
+#define IMX7ULP_VERID 0x0
+#define IMX7ULP_PARAM 0x4
+#define IMX7ULP_CR 0x10
+#define IMX7ULP_SR 0x14
+#define IMX7ULP_IER 0x18
+#define IMX7ULP_DER 0x1c
+#define IMX7ULP_CFGR0 0x20
+#define IMX7ULP_CFGR1 0x24
+#define IMX7ULP_DMR0 0x30
+#define IMX7ULP_DMR1 0x34
+#define IMX7ULP_CCR 0x40
+#define IMX7ULP_FCR 0x58
+#define IMX7ULP_FSR 0x5c
+#define IMX7ULP_TCR 0x60
+#define IMX7ULP_TDR 0x64
+#define IMX7ULP_RSR 0x70
+#define IMX7ULP_RDR 0x74
+
+/* General control register field define */
+#define CR_RRF (1 << 9)
+#define CR_RTF (1 << 8)
+#define CR_RST (1 << 1)
+#define CR_MEN (1 << 0)
+#define SR_TCF (1 << 10)
+#define SR_RDF (1 << 1)
+#define SR_TDF (1 << 0)
+#define IER_TCIE (1 << 10)
+#define IER_RDIE (1 << 1)
+#define IER_TDIE (1 << 0)
+#define CFGR1_PCSCFG (1 << 27) /* PCS[3:2] disabled */
+#define CFGR1_PCSPOL (1 << 8) /* PCS active high */
+#define CFGR1_NOSTALL (1 << 3) /* NO STALL */
+#define CFGR1_MASTER (1 << 0) /* MASTER MODE */
+#define RSR_RXEMPTY (1 << 1)
+#define TCR_CPOL (1 << 31)
+#define TCR_CPHA (1 << 30)
+#define TCR_CONT (1 << 21)
+#define TCR_CONTC (1 << 20)
+#define TCR_RXMSK (1 << 19)
+#define TCR_TXMSK (1 << 18)
+
+static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};
+
+struct lpspi_config {
+ u8 bpw;
+ u8 chip_select;
+ u8 prescale;
+ u16 mode;
+ u32 speed_hz;
+};
+
+struct fsl_lpspi_data {
+ struct spi_bitbang bitbang;
+ struct device *dev;
+
+ struct completion xfer_done;
+ void __iomem *base;
+ struct clk *clk;
+
+ void *rx_buf;
+ const void *tx_buf;
+ void (*tx)(struct fsl_lpspi_data *);
+ void (*rx)(struct fsl_lpspi_data *);
+ struct lpspi_config config;
+
+ u8 txfifosize;
+ u8 rxfifosize;
+ unsigned remain;
+};
+
+static const struct of_device_id fsl_lpspi_dt_ids[] = {
+ { .compatible = "fsl,imx7ulp-spi", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
+
+#define LPSPI_BUF_RX(type) \
+static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi) \
+{ \
+ unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR); \
+ \
+ if (fsl_lpspi->rx_buf) { \
+ *(type *)fsl_lpspi->rx_buf = val; \
+ fsl_lpspi->rx_buf += sizeof(type); \
+ } \
+}
+
+#define LPSPI_BUF_TX(type) \
+static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi) \
+{ \
+ type val = 0; \
+ \
+ if (fsl_lpspi->tx_buf) { \
+ val = *(type *)fsl_lpspi->tx_buf; \
+ fsl_lpspi->tx_buf += sizeof(type); \
+ } \
+ \
+ fsl_lpspi->remain -= sizeof(type); \
+ writel(val, fsl_lpspi->base + IMX7ULP_TDR); \
+}
+
+LPSPI_BUF_RX(u8)
+LPSPI_BUF_TX(u8)
+LPSPI_BUF_RX(u16)
+LPSPI_BUF_TX(u16)
+LPSPI_BUF_RX(u32)
+LPSPI_BUF_TX(u32)
+
+static void fsl_lpspi_intctrl(
+ struct fsl_lpspi_data *fsl_lpspi, unsigned int enable)
+{
+ writel(enable, fsl_lpspi->base + IMX7ULP_IER);
+}
+
+static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+ u8 txfifo_cnt;
+ u32 temp;
+
+ txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
+
+ while (txfifo_cnt < fsl_lpspi->txfifosize) {
+ if (!fsl_lpspi->remain)
+ break;
+ fsl_lpspi->tx(fsl_lpspi);
+ txfifo_cnt++;
+ }
+
+ if (txfifo_cnt < fsl_lpspi->txfifosize) {
+ temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
+ temp &= ~TCR_CONTC;
+ writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+ fsl_lpspi_intctrl(fsl_lpspi, IER_TCIE);
+ } else
+ fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
+}
+
+static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+ while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
+ fsl_lpspi->rx(fsl_lpspi);
+}
+
+static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi)
+{
+ u32 temp = 0;
+
+ temp |= TCR_CONT;
+ temp |= fsl_lpspi->config.bpw - 1;
+ temp |= fsl_lpspi->config.prescale << 27;
+ temp |= (fsl_lpspi->config.mode & 0x11) << 30;
+ temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
+
+ writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+ dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
+}
+
+static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
+{
+ u32 temp;
+ u8 txwatermark, rxwatermark;
+
+ temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
+
+ fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
+ fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);
+
+ rxwatermark = fsl_lpspi->txfifosize >> 1;
+ txwatermark = fsl_lpspi->rxfifosize >> 1;
+ temp = txwatermark | rxwatermark << 16;
+
+ writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
+
+ dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
+}
+
+static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
+{
+ u8 prescale;
+ unsigned int perclk_rate, scldiv;
+ struct lpspi_config config = fsl_lpspi->config;
+
+ perclk_rate = clk_get_rate(fsl_lpspi->clk);
+
+ for (prescale = 0; prescale < 8; prescale++) {
+ scldiv = perclk_rate / (clkdivs[prescale] * config.speed_hz) - 2;
+ if (scldiv < 256) {
+ fsl_lpspi->config.prescale = prescale;
+ break;
+ }
+ }
+
+ if (prescale == 8 && scldiv >= 256)
+ return -EINVAL;
+
+ writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
+
+ dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
+ perclk_rate, config.speed_hz, prescale, scldiv);
+
+ return 0;
+}
+
+static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
+{
+ int ret;
+ u32 temp;
+
+ temp = CR_RST;
+ writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+ writel(0, fsl_lpspi->base + IMX7ULP_CR);
+
+ ret = fsl_lpspi_set_bitrate(fsl_lpspi);
+ if (ret)
+ return ret;
+
+ fsl_lpspi_set_watermark(fsl_lpspi);
+
+ temp = CFGR1_PCSCFG | CFGR1_MASTER | CFGR1_NOSTALL;
+
+ /* chip select polarity */
+ if (fsl_lpspi->config.mode & SPI_CS_HIGH)
+ temp |= CFGR1_PCSPOL;
+
+ writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
+
+ temp = readl(fsl_lpspi->base + IMX7ULP_CR);
+ temp |= CR_RRF | CR_RTF | CR_MEN;
+ writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+
+ return 0;
+}
+
+static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
+{
+ u32 temp;
+ struct fsl_lpspi_data *fsl_lpspi = dev_id;
+
+ fsl_lpspi_intctrl(fsl_lpspi, 0);
+ temp = readl(fsl_lpspi->base + IMX7ULP_SR);
+
+ fsl_lpspi_read_rx_fifo(fsl_lpspi);
+
+ if ((temp & SR_TDF) && !(temp & SR_TCF)) {
+ fsl_lpspi_write_tx_fifo(fsl_lpspi);
+ return IRQ_HANDLED;
+ }
+
+ if (temp & SR_TCF) {
+ complete(&fsl_lpspi->xfer_done);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static int fsl_lpspi_setupxfer(struct spi_device *spi,
+ struct spi_transfer *t)
+{
+ struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
+
+ fsl_lpspi->config.mode = spi->mode;
+ fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
+ fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
+ fsl_lpspi->config.chip_select = spi->chip_select;
+
+ if (!fsl_lpspi->config.speed_hz)
+ fsl_lpspi->config.speed_hz = spi->max_speed_hz;
+ if (!fsl_lpspi->config.bpw)
+ fsl_lpspi->config.bpw = spi->bits_per_word;
+
+ /* Initialize the functions for transfer */
+ if (fsl_lpspi->config.bpw <= 8) {
+ fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
+ fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
+ } else if (fsl_lpspi->config.bpw <= 16) {
+ fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
+ fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
+ } else {
+ fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
+ fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
+ }
+
+ fsl_lpspi_config(fsl_lpspi);
+
+ return 0;
+}
+
+static int fsl_lpspi_transfer(struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
+
+ fsl_lpspi->tx_buf = transfer->tx_buf;
+ fsl_lpspi->rx_buf = transfer->rx_buf;
+ fsl_lpspi->remain = transfer->len;
+
+ reinit_completion(&fsl_lpspi->xfer_done);
+ fsl_lpspi_set_cmd(fsl_lpspi);
+ fsl_lpspi_write_tx_fifo(fsl_lpspi);
+ wait_for_completion(&fsl_lpspi->xfer_done);
+
+ return transfer->len;
+}
+
+/* The following funs are decided by spi framework */
+static void fsl_lpspi_chipselect(struct spi_device *spi, int is_active)
+{
+}
+
+static int fsl_lpspi_setup(struct spi_device *spi)
+{
+ return 0;
+}
+
+static void fsl_lpspi_cleanup(struct spi_device *spi)
+{
+}
+
+static int
+fsl_lpspi_prepare_message(struct spi_master *master, struct spi_message *msg)
+{
+ struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+ return clk_enable(fsl_lpspi->clk);
+}
+
+static int
+fsl_lpspi_unprepare_message(struct spi_master *master, struct spi_message *msg)
+{
+ struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+ clk_disable(fsl_lpspi->clk);
+
+ return 0;
+}
+
+static int fsl_lpspi_probe(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct fsl_lpspi_data *fsl_lpspi;
+ struct resource *res;
+ int ret, irq;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
+ if (!master)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, master);
+
+ master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
+ master->bus_num = pdev->id;
+
+ fsl_lpspi = spi_master_get_devdata(master);
+ fsl_lpspi->bitbang.master = master;
+ fsl_lpspi->dev = &pdev->dev;
+
+ fsl_lpspi->bitbang.chipselect = fsl_lpspi_chipselect;
+ fsl_lpspi->bitbang.master->setup = fsl_lpspi_setup;
+ fsl_lpspi->bitbang.master->cleanup = fsl_lpspi_cleanup;
+ fsl_lpspi->bitbang.setup_transfer = fsl_lpspi_setupxfer;
+ fsl_lpspi->bitbang.txrx_bufs = fsl_lpspi_transfer;
+ fsl_lpspi->bitbang.master->prepare_message = fsl_lpspi_prepare_message;
+ fsl_lpspi->bitbang.master->unprepare_message = fsl_lpspi_unprepare_message;
+ fsl_lpspi->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+ fsl_lpspi->bitbang.master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
+
+ init_completion(&fsl_lpspi->xfer_done);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(fsl_lpspi->base)) {
+ ret = PTR_ERR(fsl_lpspi->base);
+ goto out_master_put;
+ }
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ ret = irq;
+ goto out_master_put;
+ }
+
+ fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
+ if (IS_ERR(fsl_lpspi->clk)) {
+ ret = PTR_ERR(fsl_lpspi->clk);
+ goto out_master_put;
+ }
+
+ master->dev.of_node = pdev->dev.of_node;
+ ret = spi_bitbang_start(&fsl_lpspi->bitbang);
+ if (ret) {
+ dev_err(&pdev->dev, "bitbang start failed with %d\n", ret);
+ goto out_master_put;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
+ dev_name(&pdev->dev), fsl_lpspi);
+ if (ret) {
+ dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
+ goto out_master_put;
+ }
+
+ ret = clk_prepare(fsl_lpspi->clk);
+ if (ret)
+ goto out_master_put;
+
+ return ret;
+
+out_master_put:
+ spi_master_put(master);
+
+ return ret;
+}
+
+static int fsl_lpspi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+ spi_bitbang_stop(&fsl_lpspi->bitbang);
+
+ clk_unprepare(fsl_lpspi->clk);
+ spi_master_put(master);
+
+ return 0;
+}
+
+static struct platform_driver fsl_lpspi_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = fsl_lpspi_dt_ids,
+ },
+ .probe = fsl_lpspi_probe,
+ .remove = fsl_lpspi_remove,
+};
+module_platform_driver(fsl_lpspi_driver);
+
+MODULE_DESCRIPTION("SPI Master Controller driver");
+MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);
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