// SPDX-License-Identifier: GPL-2.0+ /* * Synopsys DesignWare 8250 driver. * * Copyright 2011 Picochip, Jamie Iles. * Copyright 2013 Intel Corporation * * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the * LCR is written whilst busy. If it is, then a busy detect interrupt is * raised, the LCR needs to be rewritten and the uart status register read. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "8250.h" /* Offsets for the DesignWare specific registers */ #define DW_UART_USR 0x1f /* UART Status Register */ #define DW_UART_DLF 0xc0 /* Divisor Latch Fraction Register */ #define DW_UART_CPR 0xf4 /* Component Parameter Register */ #define DW_UART_UCV 0xf8 /* UART Component Version */ /* Component Parameter Register bits */ #define DW_UART_CPR_ABP_DATA_WIDTH (3 << 0) #define DW_UART_CPR_AFCE_MODE (1 << 4) #define DW_UART_CPR_THRE_MODE (1 << 5) #define DW_UART_CPR_SIR_MODE (1 << 6) #define DW_UART_CPR_SIR_LP_MODE (1 << 7) #define DW_UART_CPR_ADDITIONAL_FEATURES (1 << 8) #define DW_UART_CPR_FIFO_ACCESS (1 << 9) #define DW_UART_CPR_FIFO_STAT (1 << 10) #define DW_UART_CPR_SHADOW (1 << 11) #define DW_UART_CPR_ENCODED_PARMS (1 << 12) #define DW_UART_CPR_DMA_EXTRA (1 << 13) #define DW_UART_CPR_FIFO_MODE (0xff << 16) /* Helper for fifo size calculation */ #define DW_UART_CPR_FIFO_SIZE(a) (((a >> 16) & 0xff) * 16) /* DesignWare specific register fields */ #define DW_UART_MCR_SIRE BIT(6) struct dw8250_data { u8 usr_reg; u8 dlf_size; int line; int msr_mask_on; int msr_mask_off; struct clk *clk; struct clk *pclk; struct reset_control *rst; struct uart_8250_dma dma; unsigned int skip_autocfg:1; unsigned int uart_16550_compatible:1; }; static inline u32 dw8250_readl_ext(struct uart_port *p, int offset) { if (p->iotype == UPIO_MEM32BE) return ioread32be(p->membase + offset); return readl(p->membase + offset); } static inline void dw8250_writel_ext(struct uart_port *p, int offset, u32 reg) { if (p->iotype == UPIO_MEM32BE) iowrite32be(reg, p->membase + offset); else writel(reg, p->membase + offset); } static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; /* Override any modem control signals if needed */ if (offset == UART_MSR) { value |= d->msr_mask_on; value &= ~d->msr_mask_off; } return value; } static void dw8250_force_idle(struct uart_port *p) { struct uart_8250_port *up = up_to_u8250p(p); serial8250_clear_and_reinit_fifos(up); (void)p->serial_in(p, UART_RX); } static void dw8250_check_lcr(struct uart_port *p, int value) { void __iomem *offset = p->membase + (UART_LCR << p->regshift); int tries = 1000; /* Make sure LCR write wasn't ignored */ while (tries--) { unsigned int lcr = p->serial_in(p, UART_LCR); if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR)) return; dw8250_force_idle(p); #ifdef CONFIG_64BIT if (p->type == PORT_OCTEON) __raw_writeq(value & 0xff, offset); else #endif if (p->iotype == UPIO_MEM32) writel(value, offset); else if (p->iotype == UPIO_MEM32BE) iowrite32be(value, offset); else writeb(value, offset); } /* * FIXME: this deadlocks if port->lock is already held * dev_err(p->dev, "Couldn't set LCR to %d\n", value); */ } /* Returns once the transmitter is empty or we run out of retries */ static void dw8250_tx_wait_empty(struct uart_port *p) { unsigned int tries = 20000; unsigned int delay_threshold = tries - 1000; unsigned int lsr; while (tries--) { lsr = readb (p->membase + (UART_LSR << p->regshift)); if (lsr & UART_LSR_TEMT) break; /* The device is first given a chance to empty without delay, * to avoid slowdowns at high bitrates. If after 1000 tries * the buffer has still not emptied, allow more time for low- * speed links. */ if (tries < delay_threshold) udelay (1); } } static void dw8250_serial_out38x(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; /* Allow the TX to drain before we reconfigure */ if (offset == UART_LCR) dw8250_tx_wait_empty(p); writeb(value, p->membase + (offset << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) dw8250_check_lcr(p, value); } static void dw8250_serial_out(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; writeb(value, p->membase + (offset << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) dw8250_check_lcr(p, value); } static unsigned int dw8250_serial_in(struct uart_port *p, int offset) { unsigned int value = readb(p->membase + (offset << p->regshift)); return dw8250_modify_msr(p, offset, value); } #ifdef CONFIG_64BIT static unsigned int dw8250_serial_inq(struct uart_port *p, int offset) { unsigned int value; value = (u8)__raw_readq(p->membase + (offset << p->regshift)); return dw8250_modify_msr(p, offset, value); } static void dw8250_serial_outq(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; value &= 0xff; __raw_writeq(value, p->membase + (offset << p->regshift)); /* Read back to ensure register write ordering. */ __raw_readq(p->membase + (UART_LCR << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) dw8250_check_lcr(p, value); } #endif /* CONFIG_64BIT */ static void dw8250_serial_out32(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; writel(value, p->membase + (offset << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) dw8250_check_lcr(p, value); } static unsigned int dw8250_serial_in32(struct uart_port *p, int offset) { unsigned int value = readl(p->membase + (offset << p->regshift)); return dw8250_modify_msr(p, offset, value); } static void dw8250_serial_out32be(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; iowrite32be(value, p->membase + (offset << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) dw8250_check_lcr(p, value); } static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset) { unsigned int value = ioread32be(p->membase + (offset << p->regshift)); return dw8250_modify_msr(p, offset, value); } static int dw8250_handle_irq(struct uart_port *p) { struct uart_8250_port *up = up_to_u8250p(p); struct dw8250_data *d = p->private_data; unsigned int iir = p->serial_in(p, UART_IIR); unsigned int status; unsigned long flags; /* * There are ways to get Designware-based UARTs into a state where * they are asserting UART_IIR_RX_TIMEOUT but there is no actual * data available. If we see such a case then we'll do a bogus * read. If we don't do this then the "RX TIMEOUT" interrupt will * fire forever. * * This problem has only been observed so far when not in DMA mode * so we limit the workaround only to non-DMA mode. */ if (!up->dma && ((iir & 0x3f) == UART_IIR_RX_TIMEOUT)) { spin_lock_irqsave(&p->lock, flags); status = p->serial_in(p, UART_LSR); if (!(status & (UART_LSR_DR | UART_LSR_BI))) (void) p->serial_in(p, UART_RX); spin_unlock_irqrestore(&p->lock, flags); } if (serial8250_handle_irq(p, iir)) return 1; if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) { /* Clear the USR */ (void)p->serial_in(p, d->usr_reg); return 1; } return 0; } static void dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old) { if (!state) pm_runtime_get_sync(port->dev); serial8250_do_pm(port, state, old); if (state) pm_runtime_put_sync_suspend(port->dev); } static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, struct ktermios *old) { unsigned int baud = tty_termios_baud_rate(termios); struct dw8250_data *d = p->private_data; long rate; int ret; if (IS_ERR(d->clk)) goto out; clk_disable_unprepare(d->clk); rate = clk_round_rate(d->clk, baud * 16); if (rate < 0) ret = rate; else if (rate == 0) ret = -ENOENT; else ret = clk_set_rate(d->clk, rate); clk_prepare_enable(d->clk); if (!ret) p->uartclk = rate; out: p->status &= ~UPSTAT_AUTOCTS; if (termios->c_cflag & CRTSCTS) p->status |= UPSTAT_AUTOCTS; serial8250_do_set_termios(p, termios, old); } static void dw8250_set_ldisc(struct uart_port *p, struct ktermios *termios) { struct uart_8250_port *up = up_to_u8250p(p); unsigned int mcr = p->serial_in(p, UART_MCR); if (up->capabilities & UART_CAP_IRDA) { if (termios->c_line == N_IRDA) mcr |= DW_UART_MCR_SIRE; else mcr &= ~DW_UART_MCR_SIRE; p->serial_out(p, UART_MCR, mcr); } serial8250_do_set_ldisc(p, termios); } /* * dw8250_fallback_dma_filter will prevent the UART from getting just any free * channel on platforms that have DMA engines, but don't have any channels * assigned to the UART. * * REVISIT: This is a work around for limitation in the DMA Engine API. Once the * core problem is fixed, this function is no longer needed. */ static bool dw8250_fallback_dma_filter(struct dma_chan *chan, void *param) { return false; } static bool dw8250_idma_filter(struct dma_chan *chan, void *param) { return param == chan->device->dev; } /* * divisor = div(I) + div(F) * "I" means integer, "F" means fractional * quot = div(I) = clk / (16 * baud) * frac = div(F) * 2^dlf_size * * let rem = clk % (16 * baud) * we have: div(F) * (16 * baud) = rem * so frac = 2^dlf_size * rem / (16 * baud) = (rem << dlf_size) / (16 * baud) */ static unsigned int dw8250_get_divisor(struct uart_port *p, unsigned int baud, unsigned int *frac) { unsigned int quot, rem, base_baud = baud * 16; struct dw8250_data *d = p->private_data; quot = p->uartclk / base_baud; rem = p->uartclk % base_baud; *frac = DIV_ROUND_CLOSEST(rem << d->dlf_size, base_baud); return quot; } static void dw8250_set_divisor(struct uart_port *p, unsigned int baud, unsigned int quot, unsigned int quot_frac) { dw8250_writel_ext(p, DW_UART_DLF, quot_frac); serial8250_do_set_divisor(p, baud, quot, quot_frac); } static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data) { if (p->dev->of_node) { struct device_node *np = p->dev->of_node; int id; /* get index of serial line, if found in DT aliases */ id = of_alias_get_id(np, "serial"); if (id >= 0) p->line = id; #ifdef CONFIG_64BIT if (of_device_is_compatible(np, "cavium,octeon-3860-uart")) { p->serial_in = dw8250_serial_inq; p->serial_out = dw8250_serial_outq; p->flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE; p->type = PORT_OCTEON; data->usr_reg = 0x27; data->skip_autocfg = true; } #endif if (of_device_is_big_endian(p->dev->of_node)) { p->iotype = UPIO_MEM32BE; p->serial_in = dw8250_serial_in32be; p->serial_out = dw8250_serial_out32be; } if (of_device_is_compatible(np, "marvell,armada-38x-uart")) p->serial_out = dw8250_serial_out38x; } else if (acpi_dev_present("APMC0D08", NULL, -1)) { p->iotype = UPIO_MEM32; p->regshift = 2; p->serial_in = dw8250_serial_in32; data->uart_16550_compatible = true; } /* Platforms with iDMA 64-bit */ if (platform_get_resource_byname(to_platform_device(p->dev), IORESOURCE_MEM, "lpss_priv")) { data->dma.rx_param = p->dev->parent; data->dma.tx_param = p->dev->parent; data->dma.fn = dw8250_idma_filter; } } static void dw8250_setup_port(struct uart_port *p) { struct uart_8250_port *up = up_to_u8250p(p); u32 reg; /* * If the Component Version Register returns zero, we know that * ADDITIONAL_FEATURES are not enabled. No need to go any further. */ reg = dw8250_readl_ext(p, DW_UART_UCV); if (!reg) return; dev_dbg(p->dev, "Designware UART version %c.%c%c\n", (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); dw8250_writel_ext(p, DW_UART_DLF, ~0U); reg = dw8250_readl_ext(p, DW_UART_DLF); dw8250_writel_ext(p, DW_UART_DLF, 0); if (reg) { struct dw8250_data *d = p->private_data; d->dlf_size = fls(reg); p->get_divisor = dw8250_get_divisor; p->set_divisor = dw8250_set_divisor; } reg = dw8250_readl_ext(p, DW_UART_CPR); if (!reg) return; /* Select the type based on fifo */ if (reg & DW_UART_CPR_FIFO_MODE) { p->type = PORT_16550A; p->flags |= UPF_FIXED_TYPE; p->fifosize = DW_UART_CPR_FIFO_SIZE(reg); up->capabilities = UART_CAP_FIFO; } if (reg & DW_UART_CPR_AFCE_MODE) up->capabilities |= UART_CAP_AFE; if (reg & DW_UART_CPR_SIR_MODE) up->capabilities |= UART_CAP_IRDA; } static int dw8250_probe(struct platform_device *pdev) { struct uart_8250_port uart = {}; struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); int irq = platform_get_irq(pdev, 0); struct uart_port *p = &uart.port; struct device *dev = &pdev->dev; struct dw8250_data *data; int err; u32 val; if (!regs) { dev_err(dev, "no registers defined\n"); return -EINVAL; } if (irq < 0) { if (irq != -EPROBE_DEFER) dev_err(dev, "cannot get irq\n"); return irq; } spin_lock_init(&p->lock); p->mapbase = regs->start; p->irq = irq; p->handle_irq = dw8250_handle_irq; p->pm = dw8250_do_pm; p->type = PORT_8250; p->flags = UPF_SHARE_IRQ | UPF_FIXED_PORT; p->dev = dev; p->iotype = UPIO_MEM; p->serial_in = dw8250_serial_in; p->serial_out = dw8250_serial_out; p->set_ldisc = dw8250_set_ldisc; p->set_termios = dw8250_set_termios; p->membase = devm_ioremap(dev, regs->start, resource_size(regs)); if (!p->membase) return -ENOMEM; data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->dma.fn = dw8250_fallback_dma_filter; data->usr_reg = DW_UART_USR; p->private_data = data; data->uart_16550_compatible = device_property_read_bool(dev, "snps,uart-16550-compatible"); err = device_property_read_u32(dev, "reg-shift", &val); if (!err) p->regshift = val; err = device_property_read_u32(dev, "reg-io-width", &val); if (!err && val == 4) { p->iotype = UPIO_MEM32; p->serial_in = dw8250_serial_in32; p->serial_out = dw8250_serial_out32; } if (device_property_read_bool(dev, "dcd-override")) { /* Always report DCD as active */ data->msr_mask_on |= UART_MSR_DCD; data->msr_mask_off |= UART_MSR_DDCD; } if (device_property_read_bool(dev, "dsr-override")) { /* Always report DSR as active */ data->msr_mask_on |= UART_MSR_DSR; data->msr_mask_off |= UART_MSR_DDSR; } if (device_property_read_bool(dev, "cts-override")) { /* Always report CTS as active */ data->msr_mask_on |= UART_MSR_CTS; data->msr_mask_off |= UART_MSR_DCTS; } if (device_property_read_bool(dev, "ri-override")) { /* Always report Ring indicator as inactive */ data->msr_mask_off |= UART_MSR_RI; data->msr_mask_off |= UART_MSR_TERI; } /* Always ask for fixed clock rate from a property. */ device_property_read_u32(dev, "clock-frequency", &p->uartclk); /* If there is separate baudclk, get the rate from it. */ data->clk = devm_clk_get(dev, "baudclk"); if (IS_ERR(data->clk) && PTR_ERR(data->clk) != -EPROBE_DEFER) data->clk = devm_clk_get(dev, NULL); if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER) return -EPROBE_DEFER; if (!IS_ERR_OR_NULL(data->clk)) { err = clk_prepare_enable(data->clk); if (err) dev_warn(dev, "could not enable optional baudclk: %d\n", err); else p->uartclk = clk_get_rate(data->clk); } /* If no clock rate is defined, fail. */ if (!p->uartclk) { dev_err(dev, "clock rate not defined\n"); err = -EINVAL; goto err_clk; } data->pclk = devm_clk_get(dev, "apb_pclk"); if (IS_ERR(data->pclk) && PTR_ERR(data->pclk) == -EPROBE_DEFER) { err = -EPROBE_DEFER; goto err_clk; } if (!IS_ERR(data->pclk)) { err = clk_prepare_enable(data->pclk); if (err) { dev_err(dev, "could not enable apb_pclk\n"); goto err_clk; } } data->rst = devm_reset_control_get_optional_exclusive(dev, NULL); if (IS_ERR(data->rst)) { err = PTR_ERR(data->rst); goto err_pclk; } reset_control_deassert(data->rst); dw8250_quirks(p, data); /* If the Busy Functionality is not implemented, don't handle it */ if (data->uart_16550_compatible) p->handle_irq = NULL; if (!data->skip_autocfg) dw8250_setup_port(p); /* If we have a valid fifosize, try hooking up DMA */ if (p->fifosize) { data->dma.rxconf.src_maxburst = p->fifosize / 4; data->dma.txconf.dst_maxburst = p->fifosize / 4; uart.dma = &data->dma; } data->line = serial8250_register_8250_port(&uart); if (data->line < 0) { err = data->line; goto err_reset; } platform_set_drvdata(pdev, data); pm_runtime_set_active(dev); pm_runtime_enable(dev); return 0; err_reset: reset_control_assert(data->rst); err_pclk: if (!IS_ERR(data->pclk)) clk_disable_unprepare(data->pclk); err_clk: if (!IS_ERR(data->clk)) clk_disable_unprepare(data->clk); return err; } static int dw8250_remove(struct platform_device *pdev) { struct dw8250_data *data = platform_get_drvdata(pdev); pm_runtime_get_sync(&pdev->dev); serial8250_unregister_port(data->line); reset_control_assert(data->rst); if (!IS_ERR(data->pclk)) clk_disable_unprepare(data->pclk); if (!IS_ERR(data->clk)) clk_disable_unprepare(data->clk); pm_runtime_disable(&pdev->dev); pm_runtime_put_noidle(&pdev->dev); return 0; } #ifdef CONFIG_PM_SLEEP static int dw8250_suspend(struct device *dev) { struct dw8250_data *data = dev_get_drvdata(dev); serial8250_suspend_port(data->line); return 0; } static int dw8250_resume(struct device *dev) { struct dw8250_data *data = dev_get_drvdata(dev); serial8250_resume_port(data->line); return 0; } #endif /* CONFIG_PM_SLEEP */ #ifdef CONFIG_PM static int dw8250_runtime_suspend(struct device *dev) { struct dw8250_data *data = dev_get_drvdata(dev); if (!IS_ERR(data->clk)) clk_disable_unprepare(data->clk); if (!IS_ERR(data->pclk)) clk_disable_unprepare(data->pclk); return 0; } static int dw8250_runtime_resume(struct device *dev) { struct dw8250_data *data = dev_get_drvdata(dev); if (!IS_ERR(data->pclk)) clk_prepare_enable(data->pclk); if (!IS_ERR(data->clk)) clk_prepare_enable(data->clk); return 0; } #endif static const struct dev_pm_ops dw8250_pm_ops = { SET_SYSTEM_SLEEP_PM_OPS(dw8250_suspend, dw8250_resume) SET_RUNTIME_PM_OPS(dw8250_runtime_suspend, dw8250_runtime_resume, NULL) }; static const struct of_device_id dw8250_of_match[] = { { .compatible = "snps,dw-apb-uart" }, { .compatible = "cavium,octeon-3860-uart" }, { .compatible = "marvell,armada-38x-uart" }, { .compatible = "renesas,rzn1-uart" }, { /* Sentinel */ } }; MODULE_DEVICE_TABLE(of, dw8250_of_match); static const struct acpi_device_id dw8250_acpi_match[] = { { "INT33C4", 0 }, { "INT33C5", 0 }, { "INT3434", 0 }, { "INT3435", 0 }, { "80860F0A", 0 }, { "8086228A", 0 }, { "APMC0D08", 0}, { "AMD0020", 0 }, { "AMDI0020", 0 }, { "BRCM2032", 0 }, { "HISI0031", 0 }, { }, }; MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match); static struct platform_driver dw8250_platform_driver = { .driver = { .name = "dw-apb-uart", .pm = &dw8250_pm_ops, .of_match_table = dw8250_of_match, .acpi_match_table = dw8250_acpi_match, }, .probe = dw8250_probe, .remove = dw8250_remove, }; module_platform_driver(dw8250_platform_driver); MODULE_AUTHOR("Jamie Iles"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver"); MODULE_ALIAS("platform:dw-apb-uart");