| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * OpenCores tiny SPI master driver |
| * |
| * http://opencores.org/project,tiny_spi |
| * |
| * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw> |
| * |
| * Based on spi_s3c24xx.c, which is: |
| * Copyright (c) 2006 Ben Dooks |
| * Copyright (c) 2006 Simtec Electronics |
| * Ben Dooks <ben@simtec.co.uk> |
| */ |
| |
| #include <linux/interrupt.h> |
| #include <linux/errno.h> |
| #include <linux/module.h> |
| #include <linux/platform_device.h> |
| #include <linux/spi/spi.h> |
| #include <linux/spi/spi_bitbang.h> |
| #include <linux/spi/spi_oc_tiny.h> |
| #include <linux/io.h> |
| #include <linux/gpio.h> |
| #include <linux/of.h> |
| |
| #define DRV_NAME "spi_oc_tiny" |
| |
| #define TINY_SPI_RXDATA 0 |
| #define TINY_SPI_TXDATA 4 |
| #define TINY_SPI_STATUS 8 |
| #define TINY_SPI_CONTROL 12 |
| #define TINY_SPI_BAUD 16 |
| |
| #define TINY_SPI_STATUS_TXE 0x1 |
| #define TINY_SPI_STATUS_TXR 0x2 |
| |
| struct tiny_spi { |
| /* bitbang has to be first */ |
| struct spi_bitbang bitbang; |
| struct completion done; |
| |
| void __iomem *base; |
| int irq; |
| unsigned int freq; |
| unsigned int baudwidth; |
| unsigned int baud; |
| unsigned int speed_hz; |
| unsigned int mode; |
| unsigned int len; |
| unsigned int txc, rxc; |
| const u8 *txp; |
| u8 *rxp; |
| int gpio_cs_count; |
| int *gpio_cs; |
| }; |
| |
| static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev) |
| { |
| return spi_master_get_devdata(sdev->master); |
| } |
| |
| static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz) |
| { |
| struct tiny_spi *hw = tiny_spi_to_hw(spi); |
| |
| return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1; |
| } |
| |
| static void tiny_spi_chipselect(struct spi_device *spi, int is_active) |
| { |
| struct tiny_spi *hw = tiny_spi_to_hw(spi); |
| |
| if (hw->gpio_cs_count > 0) { |
| gpio_set_value(hw->gpio_cs[spi->chip_select], |
| (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); |
| } |
| } |
| |
| static int tiny_spi_setup_transfer(struct spi_device *spi, |
| struct spi_transfer *t) |
| { |
| struct tiny_spi *hw = tiny_spi_to_hw(spi); |
| unsigned int baud = hw->baud; |
| |
| if (t) { |
| if (t->speed_hz && t->speed_hz != hw->speed_hz) |
| baud = tiny_spi_baud(spi, t->speed_hz); |
| } |
| writel(baud, hw->base + TINY_SPI_BAUD); |
| writel(hw->mode, hw->base + TINY_SPI_CONTROL); |
| return 0; |
| } |
| |
| static int tiny_spi_setup(struct spi_device *spi) |
| { |
| struct tiny_spi *hw = tiny_spi_to_hw(spi); |
| |
| if (spi->max_speed_hz != hw->speed_hz) { |
| hw->speed_hz = spi->max_speed_hz; |
| hw->baud = tiny_spi_baud(spi, hw->speed_hz); |
| } |
| hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA); |
| return 0; |
| } |
| |
| static inline void tiny_spi_wait_txr(struct tiny_spi *hw) |
| { |
| while (!(readb(hw->base + TINY_SPI_STATUS) & |
| TINY_SPI_STATUS_TXR)) |
| cpu_relax(); |
| } |
| |
| static inline void tiny_spi_wait_txe(struct tiny_spi *hw) |
| { |
| while (!(readb(hw->base + TINY_SPI_STATUS) & |
| TINY_SPI_STATUS_TXE)) |
| cpu_relax(); |
| } |
| |
| static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) |
| { |
| struct tiny_spi *hw = tiny_spi_to_hw(spi); |
| const u8 *txp = t->tx_buf; |
| u8 *rxp = t->rx_buf; |
| unsigned int i; |
| |
| if (hw->irq >= 0) { |
| /* use interrupt driven data transfer */ |
| hw->len = t->len; |
| hw->txp = t->tx_buf; |
| hw->rxp = t->rx_buf; |
| hw->txc = 0; |
| hw->rxc = 0; |
| |
| /* send the first byte */ |
| if (t->len > 1) { |
| writeb(hw->txp ? *hw->txp++ : 0, |
| hw->base + TINY_SPI_TXDATA); |
| hw->txc++; |
| writeb(hw->txp ? *hw->txp++ : 0, |
| hw->base + TINY_SPI_TXDATA); |
| hw->txc++; |
| writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS); |
| } else { |
| writeb(hw->txp ? *hw->txp++ : 0, |
| hw->base + TINY_SPI_TXDATA); |
| hw->txc++; |
| writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS); |
| } |
| |
| wait_for_completion(&hw->done); |
| } else { |
| /* we need to tighten the transfer loop */ |
| writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); |
| for (i = 1; i < t->len; i++) { |
| writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); |
| |
| if (rxp || (i != t->len - 1)) |
| tiny_spi_wait_txr(hw); |
| if (rxp) |
| *rxp++ = readb(hw->base + TINY_SPI_TXDATA); |
| } |
| tiny_spi_wait_txe(hw); |
| if (rxp) |
| *rxp++ = readb(hw->base + TINY_SPI_RXDATA); |
| } |
| |
| return t->len; |
| } |
| |
| static irqreturn_t tiny_spi_irq(int irq, void *dev) |
| { |
| struct tiny_spi *hw = dev; |
| |
| writeb(0, hw->base + TINY_SPI_STATUS); |
| if (hw->rxc + 1 == hw->len) { |
| if (hw->rxp) |
| *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA); |
| hw->rxc++; |
| complete(&hw->done); |
| } else { |
| if (hw->rxp) |
| *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA); |
| hw->rxc++; |
| if (hw->txc < hw->len) { |
| writeb(hw->txp ? *hw->txp++ : 0, |
| hw->base + TINY_SPI_TXDATA); |
| hw->txc++; |
| writeb(TINY_SPI_STATUS_TXR, |
| hw->base + TINY_SPI_STATUS); |
| } else { |
| writeb(TINY_SPI_STATUS_TXE, |
| hw->base + TINY_SPI_STATUS); |
| } |
| } |
| return IRQ_HANDLED; |
| } |
| |
| #ifdef CONFIG_OF |
| #include <linux/of_gpio.h> |
| |
| static int tiny_spi_of_probe(struct platform_device *pdev) |
| { |
| struct tiny_spi *hw = platform_get_drvdata(pdev); |
| struct device_node *np = pdev->dev.of_node; |
| unsigned int i; |
| u32 val; |
| |
| if (!np) |
| return 0; |
| hw->gpio_cs_count = of_gpio_count(np); |
| if (hw->gpio_cs_count > 0) { |
| hw->gpio_cs = devm_kcalloc(&pdev->dev, |
| hw->gpio_cs_count, sizeof(unsigned int), |
| GFP_KERNEL); |
| if (!hw->gpio_cs) |
| return -ENOMEM; |
| } |
| for (i = 0; i < hw->gpio_cs_count; i++) { |
| hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL); |
| if (hw->gpio_cs[i] < 0) |
| return -ENODEV; |
| } |
| hw->bitbang.master->dev.of_node = pdev->dev.of_node; |
| if (!of_property_read_u32(np, "clock-frequency", &val)) |
| hw->freq = val; |
| if (!of_property_read_u32(np, "baud-width", &val)) |
| hw->baudwidth = val; |
| return 0; |
| } |
| #else /* !CONFIG_OF */ |
| static int tiny_spi_of_probe(struct platform_device *pdev) |
| { |
| return 0; |
| } |
| #endif /* CONFIG_OF */ |
| |
| static int tiny_spi_probe(struct platform_device *pdev) |
| { |
| struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev); |
| struct tiny_spi *hw; |
| struct spi_master *master; |
| unsigned int i; |
| int err = -ENODEV; |
| |
| master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi)); |
| if (!master) |
| return err; |
| |
| /* setup the master state. */ |
| master->bus_num = pdev->id; |
| master->num_chipselect = 255; |
| master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; |
| master->setup = tiny_spi_setup; |
| |
| hw = spi_master_get_devdata(master); |
| platform_set_drvdata(pdev, hw); |
| |
| /* setup the state for the bitbang driver */ |
| hw->bitbang.master = master; |
| hw->bitbang.setup_transfer = tiny_spi_setup_transfer; |
| hw->bitbang.chipselect = tiny_spi_chipselect; |
| hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs; |
| |
| /* find and map our resources */ |
| hw->base = devm_platform_ioremap_resource(pdev, 0); |
| if (IS_ERR(hw->base)) { |
| err = PTR_ERR(hw->base); |
| goto exit; |
| } |
| /* irq is optional */ |
| hw->irq = platform_get_irq(pdev, 0); |
| if (hw->irq >= 0) { |
| init_completion(&hw->done); |
| err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0, |
| pdev->name, hw); |
| if (err) |
| goto exit; |
| } |
| /* find platform data */ |
| if (platp) { |
| hw->gpio_cs_count = platp->gpio_cs_count; |
| hw->gpio_cs = platp->gpio_cs; |
| if (platp->gpio_cs_count && !platp->gpio_cs) { |
| err = -EBUSY; |
| goto exit; |
| } |
| hw->freq = platp->freq; |
| hw->baudwidth = platp->baudwidth; |
| } else { |
| err = tiny_spi_of_probe(pdev); |
| if (err) |
| goto exit; |
| } |
| for (i = 0; i < hw->gpio_cs_count; i++) { |
| err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev)); |
| if (err) |
| goto exit_gpio; |
| gpio_direction_output(hw->gpio_cs[i], 1); |
| } |
| hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count); |
| |
| /* register our spi controller */ |
| err = spi_bitbang_start(&hw->bitbang); |
| if (err) |
| goto exit; |
| dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq); |
| |
| return 0; |
| |
| exit_gpio: |
| while (i-- > 0) |
| gpio_free(hw->gpio_cs[i]); |
| exit: |
| spi_master_put(master); |
| return err; |
| } |
| |
| static int tiny_spi_remove(struct platform_device *pdev) |
| { |
| struct tiny_spi *hw = platform_get_drvdata(pdev); |
| struct spi_master *master = hw->bitbang.master; |
| unsigned int i; |
| |
| spi_bitbang_stop(&hw->bitbang); |
| for (i = 0; i < hw->gpio_cs_count; i++) |
| gpio_free(hw->gpio_cs[i]); |
| spi_master_put(master); |
| return 0; |
| } |
| |
| #ifdef CONFIG_OF |
| static const struct of_device_id tiny_spi_match[] = { |
| { .compatible = "opencores,tiny-spi-rtlsvn2", }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, tiny_spi_match); |
| #endif /* CONFIG_OF */ |
| |
| static struct platform_driver tiny_spi_driver = { |
| .probe = tiny_spi_probe, |
| .remove = tiny_spi_remove, |
| .driver = { |
| .name = DRV_NAME, |
| .pm = NULL, |
| .of_match_table = of_match_ptr(tiny_spi_match), |
| }, |
| }; |
| module_platform_driver(tiny_spi_driver); |
| |
| MODULE_DESCRIPTION("OpenCores tiny SPI driver"); |
| MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS("platform:" DRV_NAME); |