Commit fcbba344 authored by Hector Martin's avatar Hector Martin Committed by Greg Kroah-Hartman
Browse files

tty: serial: samsung_tty: Add support for Apple UARTs 



Apple SoCs are a distant descendant of Samsung designs and use yet
another variant of their UART style, with different interrupt handling.

In particular, this variant has the following differences with existing
ones:

* It includes a built-in interrupt controller with different registers,
  using only a single platform IRQ

* Internal interrupt sources are treated as edge-triggered, even though
  the IRQ output is level-triggered. This chiefly affects the TX IRQ
  path: the driver can no longer rely on the TX buffer empty IRQ
  immediately firing after TX is enabled, but instead must prime the
  FIFO with data directly.

Signed-off-by: default avatarHector Martin <marcan@marcan.st>
Reviewed-by: default avatarKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Tested-by: default avatarKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210304213902.83903-25-marcan@marcan.st


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b8466833

drivers/tty/serial/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -236,7 +236,7 @@ config SERIAL_CLPS711X_CONSOLE 


config SERIAL_SAMSUNG

	tristate "Samsung SoC serial support"

	depends on PLAT_SAMSUNG || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST

	depends on PLAT_SAMSUNG || ARCH_S5PV210 || ARCH_EXYNOS || ARCH_APPLE || COMPILE_TEST

	select SERIAL_CORE

	help

	  Support for the on-chip UARTs on the Samsung S3C24XX series CPUs,

drivers/tty/serial/samsung_tty.c

+230 −8
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ 
enum s3c24xx_port_type {

	TYPE_S3C24XX,

	TYPE_S3C6400,

	TYPE_APPLE_S5L,

};



struct s3c24xx_uart_info {
@@ -151,6 +152,8 @@ struct s3c24xx_uart_port { 
#endif

};



static void s3c24xx_serial_tx_chars(struct s3c24xx_uart_port *ourport);



/* conversion functions */



#define s3c24xx_dev_to_port(__dev) dev_get_drvdata(__dev)
@@ -290,6 +293,9 @@ static void s3c24xx_serial_stop_tx(struct uart_port *port) 
	case TYPE_S3C6400:

		s3c24xx_set_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);

		break;

	case TYPE_APPLE_S5L:

		s3c24xx_clear_bit(port, APPLE_S5L_UCON_TXTHRESH_ENA, S3C2410_UCON);

		break;

	default:

		disable_irq_nosync(ourport->tx_irq);

		break;
@@ -358,6 +364,9 @@ static void enable_tx_dma(struct s3c24xx_uart_port *ourport) 
	case TYPE_S3C6400:

		s3c24xx_set_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);

		break;

	case TYPE_APPLE_S5L:

		WARN_ON(1); // No DMA

		break;

	default:

		disable_irq_nosync(ourport->tx_irq);

		break;
@@ -396,12 +405,23 @@ static void enable_tx_pio(struct s3c24xx_uart_port *ourport) 
		s3c24xx_clear_bit(port, S3C64XX_UINTM_TXD,

				  S3C64XX_UINTM);

		break;

	case TYPE_APPLE_S5L:

		ucon |= APPLE_S5L_UCON_TXTHRESH_ENA_MSK;

		wr_regl(port, S3C2410_UCON, ucon);

		break;

	default:

		enable_irq(ourport->tx_irq);

		break;

	}



	ourport->tx_mode = S3C24XX_TX_PIO;



	/*

	 * The Apple version only has edge triggered TX IRQs, so we need

	 * to kick off the process by sending some characters here.

	 */

	if (ourport->info->type == TYPE_APPLE_S5L)

		s3c24xx_serial_tx_chars(ourport);

}



static void s3c24xx_serial_start_tx_pio(struct s3c24xx_uart_port *ourport)
@@ -527,6 +547,10 @@ static void s3c24xx_serial_stop_rx(struct uart_port *port) 
			s3c24xx_set_bit(port, S3C64XX_UINTM_RXD,

					S3C64XX_UINTM);

			break;

		case TYPE_APPLE_S5L:

			s3c24xx_clear_bit(port, APPLE_S5L_UCON_RXTHRESH_ENA, S3C2410_UCON);

			s3c24xx_clear_bit(port, APPLE_S5L_UCON_RXTO_ENA, S3C2410_UCON);

			break;

		default:

			disable_irq_nosync(ourport->rx_irq);

			break;
@@ -664,14 +688,18 @@ static void enable_rx_pio(struct s3c24xx_uart_port *ourport) 


	/* set Rx mode to DMA mode */

	ucon = rd_regl(port, S3C2410_UCON);

	ucon &= ~S3C64XX_UCON_RXMODE_MASK;

	ucon |= S3C64XX_UCON_RXMODE_CPU;



	/* Apple types use these bits for IRQ masks */

	if (ourport->info->type != TYPE_APPLE_S5L) {

		ucon &= ~(S3C64XX_UCON_TIMEOUT_MASK |

				S3C64XX_UCON_EMPTYINT_EN |

				S3C64XX_UCON_DMASUS_EN |

			S3C64XX_UCON_TIMEOUT_EN |

			S3C64XX_UCON_RXMODE_MASK);

				S3C64XX_UCON_TIMEOUT_EN);

		ucon |= 0xf << S3C64XX_UCON_TIMEOUT_SHIFT |

			S3C64XX_UCON_TIMEOUT_EN |

			S3C64XX_UCON_RXMODE_CPU;

				S3C64XX_UCON_TIMEOUT_EN;

	}

	wr_regl(port, S3C2410_UCON, ucon);



	ourport->rx_mode = S3C24XX_RX_PIO;
@@ -935,6 +963,27 @@ static irqreturn_t s3c64xx_serial_handle_irq(int irq, void *id) 
	return ret;

}



/* interrupt handler for Apple SoC's.*/

static irqreturn_t apple_serial_handle_irq(int irq, void *id)

{

	struct s3c24xx_uart_port *ourport = id;

	struct uart_port *port = &ourport->port;

	unsigned int pend = rd_regl(port, S3C2410_UTRSTAT);

	irqreturn_t ret = IRQ_NONE;



	if (pend & (APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO)) {

		wr_regl(port, S3C2410_UTRSTAT,

			APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO);

		ret = s3c24xx_serial_rx_irq(irq, id);

	}

	if (pend & APPLE_S5L_UTRSTAT_TXTHRESH) {

		wr_regl(port, S3C2410_UTRSTAT, APPLE_S5L_UTRSTAT_TXTHRESH);

		ret = s3c24xx_serial_tx_irq(irq, id);

	}



	return ret;

}



static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)

{

	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
@@ -1154,6 +1203,32 @@ static void s3c64xx_serial_shutdown(struct uart_port *port) 
	ourport->tx_in_progress = 0;

}



static void apple_s5l_serial_shutdown(struct uart_port *port)

{

	struct s3c24xx_uart_port *ourport = to_ourport(port);



	unsigned int ucon;



	ucon = rd_regl(port, S3C2410_UCON);

	ucon &= ~(APPLE_S5L_UCON_TXTHRESH_ENA_MSK |

		  APPLE_S5L_UCON_RXTHRESH_ENA_MSK |

		  APPLE_S5L_UCON_RXTO_ENA_MSK);

	wr_regl(port, S3C2410_UCON, ucon);



	wr_regl(port, S3C2410_UTRSTAT, APPLE_S5L_UTRSTAT_ALL_FLAGS);



	free_irq(port->irq, ourport);



	ourport->tx_enabled = 0;

	ourport->tx_mode = 0;

	ourport->rx_enabled = 0;



	if (ourport->dma)

		s3c24xx_serial_release_dma(ourport);



	ourport->tx_in_progress = 0;

}



static int s3c24xx_serial_startup(struct uart_port *port)

{

	struct s3c24xx_uart_port *ourport = to_ourport(port);
@@ -1241,6 +1316,45 @@ static int s3c64xx_serial_startup(struct uart_port *port) 
	return ret;

}



static int apple_s5l_serial_startup(struct uart_port *port)

{

	struct s3c24xx_uart_port *ourport = to_ourport(port);

	unsigned long flags;

	unsigned int ufcon;

	int ret;



	wr_regl(port, S3C2410_UTRSTAT, APPLE_S5L_UTRSTAT_ALL_FLAGS);



	ret = request_irq(port->irq, apple_serial_handle_irq, 0,

			  s3c24xx_serial_portname(port), ourport);

	if (ret) {

		dev_err(port->dev, "cannot get irq %d\n", port->irq);

		return ret;

	}



	/* For compatibility with s3c24xx Soc's */

	ourport->rx_enabled = 1;

	ourport->tx_enabled = 0;



	spin_lock_irqsave(&port->lock, flags);



	ufcon = rd_regl(port, S3C2410_UFCON);

	ufcon |= S3C2410_UFCON_RESETRX | S5PV210_UFCON_RXTRIG8;

	if (!uart_console(port))

		ufcon |= S3C2410_UFCON_RESETTX;

	wr_regl(port, S3C2410_UFCON, ufcon);



	enable_rx_pio(ourport);



	spin_unlock_irqrestore(&port->lock, flags);



	/* Enable Rx Interrupt */

	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTHRESH_ENA, S3C2410_UCON);

	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTO_ENA, S3C2410_UCON);



	return ret;

}



/* power power management control */



static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level,
@@ -1568,6 +1682,8 @@ static const char *s3c24xx_serial_type(struct uart_port *port) 
		return "S3C24XX";

	case TYPE_S3C6400:

		return "S3C6400/10";

	case TYPE_APPLE_S5L:

		return "APPLE S5L";

	default:

		return NULL;

	}
@@ -1659,6 +1775,27 @@ static const struct uart_ops s3c64xx_serial_ops = { 
#endif

};



static const struct uart_ops apple_s5l_serial_ops = {

	.pm		= s3c24xx_serial_pm,

	.tx_empty	= s3c24xx_serial_tx_empty,

	.get_mctrl	= s3c24xx_serial_get_mctrl,

	.set_mctrl	= s3c24xx_serial_set_mctrl,

	.stop_tx	= s3c24xx_serial_stop_tx,

	.start_tx	= s3c24xx_serial_start_tx,

	.stop_rx	= s3c24xx_serial_stop_rx,

	.break_ctl	= s3c24xx_serial_break_ctl,

	.startup	= apple_s5l_serial_startup,

	.shutdown	= apple_s5l_serial_shutdown,

	.set_termios	= s3c24xx_serial_set_termios,

	.type		= s3c24xx_serial_type,

	.config_port	= s3c24xx_serial_config_port,

	.verify_port	= s3c24xx_serial_verify_port,

#if defined(CONFIG_SERIAL_SAMSUNG_CONSOLE) && defined(CONFIG_CONSOLE_POLL)

	.poll_get_char = s3c24xx_serial_get_poll_char,

	.poll_put_char = s3c24xx_serial_put_poll_char,

#endif

};



static struct uart_driver s3c24xx_uart_drv = {

	.owner		= THIS_MODULE,

	.driver_name	= "s3c2410_serial",
@@ -1975,6 +2112,18 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, 
		wr_regl(port, S3C64XX_UINTP, 0xf);

		wr_regl(port, S3C64XX_UINTSP, 0xf);

		break;

	case TYPE_APPLE_S5L: {

		unsigned int ucon;



		ucon = rd_regl(port, S3C2410_UCON);

		ucon &= ~(APPLE_S5L_UCON_TXTHRESH_ENA_MSK |

			APPLE_S5L_UCON_RXTHRESH_ENA_MSK |

			APPLE_S5L_UCON_RXTO_ENA_MSK);

		wr_regl(port, S3C2410_UCON, ucon);



		wr_regl(port, S3C2410_UTRSTAT, APPLE_S5L_UTRSTAT_ALL_FLAGS);

		break;

	}

	default:

		break;

	}
@@ -2054,6 +2203,9 @@ static int s3c24xx_serial_probe(struct platform_device *pdev) 
	case TYPE_S3C6400:

		ourport->port.ops = &s3c64xx_serial_ops;

		break;

	case TYPE_APPLE_S5L:

		ourport->port.ops = &apple_s5l_serial_ops;

		break;

	}



	if (np) {
@@ -2196,6 +2348,43 @@ static int s3c24xx_serial_resume_noirq(struct device *dev) 
			clk_disable_unprepare(ourport->clk);

			break;

		}

		case TYPE_APPLE_S5L: {

			unsigned int ucon;

			int ret;



			ret = clk_prepare_enable(ourport->clk);

			if (ret) {

				dev_err(dev, "clk_enable clk failed: %d\n", ret);

				return ret;

			}

			if (!IS_ERR(ourport->baudclk)) {

				ret = clk_prepare_enable(ourport->baudclk);

				if (ret) {

					dev_err(dev, "clk_enable baudclk failed: %d\n", ret);

					clk_disable_unprepare(ourport->clk);

					return ret;

				}

			}



			ucon = rd_regl(port, S3C2410_UCON);



			ucon &= ~(APPLE_S5L_UCON_TXTHRESH_ENA_MSK |

				  APPLE_S5L_UCON_RXTHRESH_ENA_MSK |

				  APPLE_S5L_UCON_RXTO_ENA_MSK);



			if (ourport->tx_enabled)

				ucon |= APPLE_S5L_UCON_TXTHRESH_ENA_MSK;

			if (ourport->rx_enabled)

				ucon |= APPLE_S5L_UCON_RXTHRESH_ENA_MSK |

					APPLE_S5L_UCON_RXTO_ENA_MSK;



			wr_regl(port, S3C2410_UCON, ucon);



			if (!IS_ERR(ourport->baudclk))

				clk_disable_unprepare(ourport->baudclk);

			clk_disable_unprepare(ourport->clk);

			break;

		}

		default:

			break;

		}
@@ -2605,6 +2794,34 @@ static struct s3c24xx_serial_drv_data exynos5433_serial_drv_data = { 
#define EXYNOS5433_SERIAL_DRV_DATA (kernel_ulong_t)NULL

#endif



#ifdef CONFIG_ARCH_APPLE

static struct s3c24xx_serial_drv_data s5l_serial_drv_data = {

	.info = &(struct s3c24xx_uart_info) {

		.name		= "Apple S5L UART",

		.type		= TYPE_APPLE_S5L,

		.port_type	= PORT_8250,

		.fifosize	= 16,

		.rx_fifomask	= S3C2410_UFSTAT_RXMASK,

		.rx_fifoshift	= S3C2410_UFSTAT_RXSHIFT,

		.rx_fifofull	= S3C2410_UFSTAT_RXFULL,

		.tx_fifofull	= S3C2410_UFSTAT_TXFULL,

		.tx_fifomask	= S3C2410_UFSTAT_TXMASK,

		.tx_fifoshift	= S3C2410_UFSTAT_TXSHIFT,

		.def_clk_sel	= S3C2410_UCON_CLKSEL0,

		.num_clks	= 1,

		.clksel_mask	= 0,

		.clksel_shift	= 0,

	},

	.def_cfg = &(struct s3c2410_uartcfg) {

		.ucon		= APPLE_S5L_UCON_DEFAULT,

		.ufcon		= S3C2410_UFCON_DEFAULT,

	},

};

#define S5L_SERIAL_DRV_DATA ((kernel_ulong_t)&s5l_serial_drv_data)

#else

#define S5L_SERIAL_DRV_DATA ((kernel_ulong_t)NULL)

#endif



static const struct platform_device_id s3c24xx_serial_driver_ids[] = {

	{

		.name		= "s3c2410-uart",
@@ -2627,6 +2844,9 @@ static const struct platform_device_id s3c24xx_serial_driver_ids[] = { 
	}, {

		.name		= "exynos5433-uart",

		.driver_data	= EXYNOS5433_SERIAL_DRV_DATA,

	}, {

		.name		= "s5l-uart",

		.driver_data	= S5L_SERIAL_DRV_DATA,

	},

	{ },

};
@@ -2648,6 +2868,8 @@ static const struct of_device_id s3c24xx_uart_dt_match[] = { 
		.data = (void *)EXYNOS4210_SERIAL_DRV_DATA },

	{ .compatible = "samsung,exynos5433-uart",

		.data = (void *)EXYNOS5433_SERIAL_DRV_DATA },

	{ .compatible = "apple,s5l-uart",

		.data = (void *)S5L_SERIAL_DRV_DATA },

	{},

};

MODULE_DEVICE_TABLE(of, s3c24xx_uart_dt_match);

include/linux/serial_s3c.h

+16 −0
Original line number Diff line number Diff line
@@ -246,6 +246,22 @@ 
				 S5PV210_UFCON_TXTRIG4 |	\

				 S5PV210_UFCON_RXTRIG4)



#define APPLE_S5L_UCON_RXTO_ENA		9

#define APPLE_S5L_UCON_RXTHRESH_ENA	12

#define APPLE_S5L_UCON_TXTHRESH_ENA	13

#define APPLE_S5L_UCON_RXTO_ENA_MSK	(1 << APPLE_S5L_UCON_RXTO_ENA)

#define APPLE_S5L_UCON_RXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_RXTHRESH_ENA)

#define APPLE_S5L_UCON_TXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_TXTHRESH_ENA)



#define APPLE_S5L_UCON_DEFAULT		(S3C2410_UCON_TXIRQMODE | \

					 S3C2410_UCON_RXIRQMODE | \

					 S3C2410_UCON_RXFIFO_TOI)



#define APPLE_S5L_UTRSTAT_RXTHRESH	(1<<4)

#define APPLE_S5L_UTRSTAT_TXTHRESH	(1<<5)

#define APPLE_S5L_UTRSTAT_RXTO		(1<<9)

#define APPLE_S5L_UTRSTAT_ALL_FLAGS	(0x3f0)



#ifndef __ASSEMBLY__



#include <linux/serial_core.h>