diff options
Diffstat (limited to 'drivers/spi/spi-at91-usart.c')
| -rw-r--r-- | drivers/spi/spi-at91-usart.c | 675 |
1 files changed, 675 insertions, 0 deletions
diff --git a/drivers/spi/spi-at91-usart.c b/drivers/spi/spi-at91-usart.c new file mode 100644 index 0000000000..b11d0f993c --- /dev/null +++ b/drivers/spi/spi-at91-usart.c @@ -0,0 +1,675 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Driver for AT91 USART Controllers as SPI +// +// Copyright (C) 2018 Microchip Technology Inc. +// +// Author: Radu Pirea <radu.pirea@microchip.com> + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/dmaengine.h> +#include <linux/dma-direction.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/gpio/consumer.h> +#include <linux/pinctrl/consumer.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> + +#include <linux/spi/spi.h> + +#define US_CR 0x00 +#define US_MR 0x04 +#define US_IER 0x08 +#define US_IDR 0x0C +#define US_CSR 0x14 +#define US_RHR 0x18 +#define US_THR 0x1C +#define US_BRGR 0x20 +#define US_VERSION 0xFC + +#define US_CR_RSTRX BIT(2) +#define US_CR_RSTTX BIT(3) +#define US_CR_RXEN BIT(4) +#define US_CR_RXDIS BIT(5) +#define US_CR_TXEN BIT(6) +#define US_CR_TXDIS BIT(7) + +#define US_MR_SPI_HOST 0x0E +#define US_MR_CHRL GENMASK(7, 6) +#define US_MR_CPHA BIT(8) +#define US_MR_CPOL BIT(16) +#define US_MR_CLKO BIT(18) +#define US_MR_WRDBT BIT(20) +#define US_MR_LOOP BIT(15) + +#define US_IR_RXRDY BIT(0) +#define US_IR_TXRDY BIT(1) +#define US_IR_OVRE BIT(5) + +#define US_BRGR_SIZE BIT(16) + +#define US_MIN_CLK_DIV 0x06 +#define US_MAX_CLK_DIV BIT(16) + +#define US_RESET (US_CR_RSTRX | US_CR_RSTTX) +#define US_DISABLE (US_CR_RXDIS | US_CR_TXDIS) +#define US_ENABLE (US_CR_RXEN | US_CR_TXEN) +#define US_OVRE_RXRDY_IRQS (US_IR_OVRE | US_IR_RXRDY) + +#define US_INIT \ + (US_MR_SPI_HOST | US_MR_CHRL | US_MR_CLKO | US_MR_WRDBT) +#define US_DMA_MIN_BYTES 16 +#define US_DMA_TIMEOUT (msecs_to_jiffies(1000)) + +/* Register access macros */ +#define at91_usart_spi_readl(port, reg) \ + readl_relaxed((port)->regs + US_##reg) +#define at91_usart_spi_writel(port, reg, value) \ + writel_relaxed((value), (port)->regs + US_##reg) + +#define at91_usart_spi_readb(port, reg) \ + readb_relaxed((port)->regs + US_##reg) +#define at91_usart_spi_writeb(port, reg, value) \ + writeb_relaxed((value), (port)->regs + US_##reg) + +struct at91_usart_spi { + struct platform_device *mpdev; + struct spi_transfer *current_transfer; + void __iomem *regs; + struct device *dev; + struct clk *clk; + + struct completion xfer_completion; + + /*used in interrupt to protect data reading*/ + spinlock_t lock; + + phys_addr_t phybase; + + int irq; + unsigned int current_tx_remaining_bytes; + unsigned int current_rx_remaining_bytes; + + u32 spi_clk; + u32 status; + + bool xfer_failed; + bool use_dma; +}; + +static void dma_callback(void *data) +{ + struct spi_controller *ctlr = data; + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + + at91_usart_spi_writel(aus, IER, US_IR_RXRDY); + aus->current_rx_remaining_bytes = 0; + complete(&aus->xfer_completion); +} + +static bool at91_usart_spi_can_dma(struct spi_controller *ctrl, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(ctrl); + + return aus->use_dma && xfer->len >= US_DMA_MIN_BYTES; +} + +static int at91_usart_spi_configure_dma(struct spi_controller *ctlr, + struct at91_usart_spi *aus) +{ + struct dma_slave_config slave_config; + struct device *dev = &aus->mpdev->dev; + phys_addr_t phybase = aus->phybase; + dma_cap_mask_t mask; + int err = 0; + + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + + ctlr->dma_tx = dma_request_chan(dev, "tx"); + if (IS_ERR_OR_NULL(ctlr->dma_tx)) { + if (IS_ERR(ctlr->dma_tx)) { + err = PTR_ERR(ctlr->dma_tx); + goto at91_usart_spi_error_clear; + } + + dev_dbg(dev, + "DMA TX channel not available, SPI unable to use DMA\n"); + err = -EBUSY; + goto at91_usart_spi_error_clear; + } + + ctlr->dma_rx = dma_request_chan(dev, "rx"); + if (IS_ERR_OR_NULL(ctlr->dma_rx)) { + if (IS_ERR(ctlr->dma_rx)) { + err = PTR_ERR(ctlr->dma_rx); + goto at91_usart_spi_error; + } + + dev_dbg(dev, + "DMA RX channel not available, SPI unable to use DMA\n"); + err = -EBUSY; + goto at91_usart_spi_error; + } + + slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + slave_config.dst_addr = (dma_addr_t)phybase + US_THR; + slave_config.src_addr = (dma_addr_t)phybase + US_RHR; + slave_config.src_maxburst = 1; + slave_config.dst_maxburst = 1; + slave_config.device_fc = false; + + slave_config.direction = DMA_DEV_TO_MEM; + if (dmaengine_slave_config(ctlr->dma_rx, &slave_config)) { + dev_err(&ctlr->dev, + "failed to configure rx dma channel\n"); + err = -EINVAL; + goto at91_usart_spi_error; + } + + slave_config.direction = DMA_MEM_TO_DEV; + if (dmaengine_slave_config(ctlr->dma_tx, &slave_config)) { + dev_err(&ctlr->dev, + "failed to configure tx dma channel\n"); + err = -EINVAL; + goto at91_usart_spi_error; + } + + aus->use_dma = true; + return 0; + +at91_usart_spi_error: + if (!IS_ERR_OR_NULL(ctlr->dma_tx)) + dma_release_channel(ctlr->dma_tx); + if (!IS_ERR_OR_NULL(ctlr->dma_rx)) + dma_release_channel(ctlr->dma_rx); + ctlr->dma_tx = NULL; + ctlr->dma_rx = NULL; + +at91_usart_spi_error_clear: + return err; +} + +static void at91_usart_spi_release_dma(struct spi_controller *ctlr) +{ + if (ctlr->dma_rx) + dma_release_channel(ctlr->dma_rx); + if (ctlr->dma_tx) + dma_release_channel(ctlr->dma_tx); +} + +static void at91_usart_spi_stop_dma(struct spi_controller *ctlr) +{ + if (ctlr->dma_rx) + dmaengine_terminate_all(ctlr->dma_rx); + if (ctlr->dma_tx) + dmaengine_terminate_all(ctlr->dma_tx); +} + +static int at91_usart_spi_dma_transfer(struct spi_controller *ctlr, + struct spi_transfer *xfer) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + struct dma_chan *rxchan = ctlr->dma_rx; + struct dma_chan *txchan = ctlr->dma_tx; + struct dma_async_tx_descriptor *rxdesc; + struct dma_async_tx_descriptor *txdesc; + dma_cookie_t cookie; + + /* Disable RX interrupt */ + at91_usart_spi_writel(aus, IDR, US_IR_RXRDY); + + rxdesc = dmaengine_prep_slave_sg(rxchan, + xfer->rx_sg.sgl, + xfer->rx_sg.nents, + DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT | + DMA_CTRL_ACK); + if (!rxdesc) + goto at91_usart_spi_err_dma; + + txdesc = dmaengine_prep_slave_sg(txchan, + xfer->tx_sg.sgl, + xfer->tx_sg.nents, + DMA_MEM_TO_DEV, + DMA_PREP_INTERRUPT | + DMA_CTRL_ACK); + if (!txdesc) + goto at91_usart_spi_err_dma; + + rxdesc->callback = dma_callback; + rxdesc->callback_param = ctlr; + + cookie = rxdesc->tx_submit(rxdesc); + if (dma_submit_error(cookie)) + goto at91_usart_spi_err_dma; + + cookie = txdesc->tx_submit(txdesc); + if (dma_submit_error(cookie)) + goto at91_usart_spi_err_dma; + + rxchan->device->device_issue_pending(rxchan); + txchan->device->device_issue_pending(txchan); + + return 0; + +at91_usart_spi_err_dma: + /* Enable RX interrupt if something fails and fallback to PIO */ + at91_usart_spi_writel(aus, IER, US_IR_RXRDY); + at91_usart_spi_stop_dma(ctlr); + + return -ENOMEM; +} + +static unsigned long at91_usart_spi_dma_timeout(struct at91_usart_spi *aus) +{ + return wait_for_completion_timeout(&aus->xfer_completion, + US_DMA_TIMEOUT); +} + +static inline u32 at91_usart_spi_tx_ready(struct at91_usart_spi *aus) +{ + return aus->status & US_IR_TXRDY; +} + +static inline u32 at91_usart_spi_rx_ready(struct at91_usart_spi *aus) +{ + return aus->status & US_IR_RXRDY; +} + +static inline u32 at91_usart_spi_check_overrun(struct at91_usart_spi *aus) +{ + return aus->status & US_IR_OVRE; +} + +static inline u32 at91_usart_spi_read_status(struct at91_usart_spi *aus) +{ + aus->status = at91_usart_spi_readl(aus, CSR); + return aus->status; +} + +static inline void at91_usart_spi_tx(struct at91_usart_spi *aus) +{ + unsigned int len = aus->current_transfer->len; + unsigned int remaining = aus->current_tx_remaining_bytes; + const u8 *tx_buf = aus->current_transfer->tx_buf; + + if (!remaining) + return; + + if (at91_usart_spi_tx_ready(aus)) { + at91_usart_spi_writeb(aus, THR, tx_buf[len - remaining]); + aus->current_tx_remaining_bytes--; + } +} + +static inline void at91_usart_spi_rx(struct at91_usart_spi *aus) +{ + int len = aus->current_transfer->len; + int remaining = aus->current_rx_remaining_bytes; + u8 *rx_buf = aus->current_transfer->rx_buf; + + if (!remaining) + return; + + rx_buf[len - remaining] = at91_usart_spi_readb(aus, RHR); + aus->current_rx_remaining_bytes--; +} + +static inline void +at91_usart_spi_set_xfer_speed(struct at91_usart_spi *aus, + struct spi_transfer *xfer) +{ + at91_usart_spi_writel(aus, BRGR, + DIV_ROUND_UP(aus->spi_clk, xfer->speed_hz)); +} + +static irqreturn_t at91_usart_spi_interrupt(int irq, void *dev_id) +{ + struct spi_controller *controller = dev_id; + struct at91_usart_spi *aus = spi_controller_get_devdata(controller); + + spin_lock(&aus->lock); + at91_usart_spi_read_status(aus); + + if (at91_usart_spi_check_overrun(aus)) { + aus->xfer_failed = true; + at91_usart_spi_writel(aus, IDR, US_IR_OVRE | US_IR_RXRDY); + spin_unlock(&aus->lock); + return IRQ_HANDLED; + } + + if (at91_usart_spi_rx_ready(aus)) { + at91_usart_spi_rx(aus); + spin_unlock(&aus->lock); + return IRQ_HANDLED; + } + + spin_unlock(&aus->lock); + + return IRQ_NONE; +} + +static int at91_usart_spi_setup(struct spi_device *spi) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(spi->controller); + u32 *ausd = spi->controller_state; + unsigned int mr = at91_usart_spi_readl(aus, MR); + + if (spi->mode & SPI_CPOL) + mr |= US_MR_CPOL; + else + mr &= ~US_MR_CPOL; + + if (spi->mode & SPI_CPHA) + mr |= US_MR_CPHA; + else + mr &= ~US_MR_CPHA; + + if (spi->mode & SPI_LOOP) + mr |= US_MR_LOOP; + else + mr &= ~US_MR_LOOP; + + if (!ausd) { + ausd = kzalloc(sizeof(*ausd), GFP_KERNEL); + if (!ausd) + return -ENOMEM; + + spi->controller_state = ausd; + } + + *ausd = mr; + + dev_dbg(&spi->dev, + "setup: bpw %u mode 0x%x -> mr %d %08x\n", + spi->bits_per_word, spi->mode, spi_get_chipselect(spi, 0), mr); + + return 0; +} + +static int at91_usart_spi_transfer_one(struct spi_controller *ctlr, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + unsigned long dma_timeout = 0; + int ret = 0; + + at91_usart_spi_set_xfer_speed(aus, xfer); + aus->xfer_failed = false; + aus->current_transfer = xfer; + aus->current_tx_remaining_bytes = xfer->len; + aus->current_rx_remaining_bytes = xfer->len; + + while ((aus->current_tx_remaining_bytes || + aus->current_rx_remaining_bytes) && !aus->xfer_failed) { + reinit_completion(&aus->xfer_completion); + if (at91_usart_spi_can_dma(ctlr, spi, xfer) && + !ret) { + ret = at91_usart_spi_dma_transfer(ctlr, xfer); + if (ret) + continue; + + dma_timeout = at91_usart_spi_dma_timeout(aus); + + if (WARN_ON(dma_timeout == 0)) { + dev_err(&spi->dev, "DMA transfer timeout\n"); + return -EIO; + } + aus->current_tx_remaining_bytes = 0; + } else { + at91_usart_spi_read_status(aus); + at91_usart_spi_tx(aus); + } + + cpu_relax(); + } + + if (aus->xfer_failed) { + dev_err(aus->dev, "Overrun!\n"); + return -EIO; + } + + return 0; +} + +static int at91_usart_spi_prepare_message(struct spi_controller *ctlr, + struct spi_message *message) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + struct spi_device *spi = message->spi; + u32 *ausd = spi->controller_state; + + at91_usart_spi_writel(aus, CR, US_ENABLE); + at91_usart_spi_writel(aus, IER, US_OVRE_RXRDY_IRQS); + at91_usart_spi_writel(aus, MR, *ausd); + + return 0; +} + +static int at91_usart_spi_unprepare_message(struct spi_controller *ctlr, + struct spi_message *message) +{ + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + + at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE); + at91_usart_spi_writel(aus, IDR, US_OVRE_RXRDY_IRQS); + + return 0; +} + +static void at91_usart_spi_cleanup(struct spi_device *spi) +{ + struct at91_usart_spi_device *ausd = spi->controller_state; + + spi->controller_state = NULL; + kfree(ausd); +} + +static void at91_usart_spi_init(struct at91_usart_spi *aus) +{ + at91_usart_spi_writel(aus, MR, US_INIT); + at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE); +} + +static int at91_usart_gpio_setup(struct platform_device *pdev) +{ + struct gpio_descs *cs_gpios; + + cs_gpios = devm_gpiod_get_array_optional(&pdev->dev, "cs", GPIOD_OUT_LOW); + + return PTR_ERR_OR_ZERO(cs_gpios); +} + +static int at91_usart_spi_probe(struct platform_device *pdev) +{ + struct resource *regs; + struct spi_controller *controller; + struct at91_usart_spi *aus; + struct clk *clk; + int irq; + int ret; + + regs = platform_get_resource(to_platform_device(pdev->dev.parent), + IORESOURCE_MEM, 0); + if (!regs) + return -EINVAL; + + irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0); + if (irq < 0) + return irq; + + clk = devm_clk_get(pdev->dev.parent, "usart"); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + ret = -ENOMEM; + controller = spi_alloc_host(&pdev->dev, sizeof(*aus)); + if (!controller) + goto at91_usart_spi_probe_fail; + + ret = at91_usart_gpio_setup(pdev); + if (ret) + goto at91_usart_spi_probe_fail; + + controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH; + controller->dev.of_node = pdev->dev.parent->of_node; + controller->bits_per_word_mask = SPI_BPW_MASK(8); + controller->setup = at91_usart_spi_setup; + controller->flags = SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX; + controller->transfer_one = at91_usart_spi_transfer_one; + controller->prepare_message = at91_usart_spi_prepare_message; + controller->unprepare_message = at91_usart_spi_unprepare_message; + controller->can_dma = at91_usart_spi_can_dma; + controller->cleanup = at91_usart_spi_cleanup; + controller->max_speed_hz = DIV_ROUND_UP(clk_get_rate(clk), + US_MIN_CLK_DIV); + controller->min_speed_hz = DIV_ROUND_UP(clk_get_rate(clk), + US_MAX_CLK_DIV); + platform_set_drvdata(pdev, controller); + + aus = spi_controller_get_devdata(controller); + + aus->dev = &pdev->dev; + aus->regs = devm_ioremap_resource(&pdev->dev, regs); + if (IS_ERR(aus->regs)) { + ret = PTR_ERR(aus->regs); + goto at91_usart_spi_probe_fail; + } + + aus->irq = irq; + aus->clk = clk; + + ret = devm_request_irq(&pdev->dev, irq, at91_usart_spi_interrupt, 0, + dev_name(&pdev->dev), controller); + if (ret) + goto at91_usart_spi_probe_fail; + + ret = clk_prepare_enable(clk); + if (ret) + goto at91_usart_spi_probe_fail; + + aus->spi_clk = clk_get_rate(clk); + at91_usart_spi_init(aus); + + aus->phybase = regs->start; + + aus->mpdev = to_platform_device(pdev->dev.parent); + + ret = at91_usart_spi_configure_dma(controller, aus); + if (ret) + goto at91_usart_fail_dma; + + spin_lock_init(&aus->lock); + init_completion(&aus->xfer_completion); + + ret = devm_spi_register_controller(&pdev->dev, controller); + if (ret) + goto at91_usart_fail_register_controller; + + dev_info(&pdev->dev, + "AT91 USART SPI Controller version 0x%x at %pa (irq %d)\n", + at91_usart_spi_readl(aus, VERSION), + ®s->start, irq); + + return 0; + +at91_usart_fail_register_controller: + at91_usart_spi_release_dma(controller); +at91_usart_fail_dma: + clk_disable_unprepare(clk); +at91_usart_spi_probe_fail: + spi_controller_put(controller); + return ret; +} + +__maybe_unused static int at91_usart_spi_runtime_suspend(struct device *dev) +{ + struct spi_controller *ctlr = dev_get_drvdata(dev); + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + + clk_disable_unprepare(aus->clk); + pinctrl_pm_select_sleep_state(dev); + + return 0; +} + +__maybe_unused static int at91_usart_spi_runtime_resume(struct device *dev) +{ + struct spi_controller *ctrl = dev_get_drvdata(dev); + struct at91_usart_spi *aus = spi_controller_get_devdata(ctrl); + + pinctrl_pm_select_default_state(dev); + + return clk_prepare_enable(aus->clk); +} + +__maybe_unused static int at91_usart_spi_suspend(struct device *dev) +{ + struct spi_controller *ctrl = dev_get_drvdata(dev); + int ret; + + ret = spi_controller_suspend(ctrl); + if (ret) + return ret; + + if (!pm_runtime_suspended(dev)) + at91_usart_spi_runtime_suspend(dev); + + return 0; +} + +__maybe_unused static int at91_usart_spi_resume(struct device *dev) +{ + struct spi_controller *ctrl = dev_get_drvdata(dev); + struct at91_usart_spi *aus = spi_controller_get_devdata(ctrl); + int ret; + + if (!pm_runtime_suspended(dev)) { + ret = at91_usart_spi_runtime_resume(dev); + if (ret) + return ret; + } + + at91_usart_spi_init(aus); + + return spi_controller_resume(ctrl); +} + +static void at91_usart_spi_remove(struct platform_device *pdev) +{ + struct spi_controller *ctlr = platform_get_drvdata(pdev); + struct at91_usart_spi *aus = spi_controller_get_devdata(ctlr); + + at91_usart_spi_release_dma(ctlr); + clk_disable_unprepare(aus->clk); +} + +static const struct dev_pm_ops at91_usart_spi_pm_ops = { + SET_SYSTEM_SLEEP_PM_OPS(at91_usart_spi_suspend, at91_usart_spi_resume) + SET_RUNTIME_PM_OPS(at91_usart_spi_runtime_suspend, + at91_usart_spi_runtime_resume, NULL) +}; + +static struct platform_driver at91_usart_spi_driver = { + .driver = { + .name = "at91_usart_spi", + .pm = &at91_usart_spi_pm_ops, + }, + .probe = at91_usart_spi_probe, + .remove_new = at91_usart_spi_remove, +}; + +module_platform_driver(at91_usart_spi_driver); + +MODULE_DESCRIPTION("Microchip AT91 USART SPI Controller driver"); +MODULE_AUTHOR("Radu Pirea <radu.pirea@microchip.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:at91_usart_spi"); |