rtc: add driver for DS1685 family of real time clocks

This adds a driver for the Dallas/Maxim DS1685-family of RTC chips.  It
supports the DS1685/DS1687, DS1688/DS1691, DS1689/DS1693, DS17285/DS17287,
DS17485/DS17487, and DS17885/DS17887 RTC chips.  These chips are commonly
found in SGI O2 and SGI Octane systems.  It was originally derived from a
driver patch submitted by Matthias Fuchs many years ago for use in
EPPC-405-UC modules, which also used these RTCs.  In addition to the
time-keeping functions, this RTC also handles the shutdown mechanism of
the O2 and Octane and acts as a partial NVRAM for the boot PROMS in these
systems.

Verified on both an SGI O2 and an SGI Octane.

Signed-off-by: Joshua Kinard <kumba@gentoo.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 375 insertions, 0 deletions

diff --git a/include/linux/rtc/ds1685.h b/include/linux/rtc/ds1685.h
new file mode 100644
index 0000000..e6337a5
--- /dev/null
+++ b/include/linux/rtc/ds1685.h
@@ -0,0 +1,375 @@
+/*
+ * Definitions for the registers, addresses, and platform data of the
+ * DS1685/DS1687-series RTC chips.
+ *
+ * This Driver also works for the DS17X85/DS17X87 RTC chips.  Functionally
+ * similar to the DS1685/DS1687, they support a few extra features which
+ * include larger, battery-backed NV-SRAM, burst-mode access, and an RTC
+ * write counter.
+ *
+ * Copyright (C) 2011-2014 Joshua Kinard <kumba@gentoo.org>.
+ * Copyright (C) 2009 Matthias Fuchs <matthias.fuchs@esd-electronics.com>.
+ *
+ * References:
+ *    DS1685/DS1687 3V/5V Real-Time Clocks, 19-5215, Rev 4/10.
+ *    DS17x85/DS17x87 3V/5V Real-Time Clocks, 19-5222, Rev 4/10.
+ *    DS1689/DS1693 3V/5V Serialized Real-Time Clocks, Rev 112105.
+ *    Application Note 90, Using the Multiplex Bus RTC Extended Features.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _LINUX_RTC_DS1685_H_
+#define _LINUX_RTC_DS1685_H_
+
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+
+/**
+ * struct ds1685_priv - DS1685 private data structure.
+ * @dev: pointer to the rtc_device structure.
+ * @regs: iomapped base address pointer of the RTC registers.
+ * @regstep: padding/step size between registers (optional).
+ * @baseaddr: base address of the RTC device.
+ * @size: resource size.
+ * @lock: private lock variable for spin locking/unlocking.
+ * @work: private workqueue.
+ * @irq: IRQ number assigned to the RTC device.
+ * @prepare_poweroff: pointer to platform pre-poweroff function.
+ * @wake_alarm: pointer to platform wake alarm function.
+ * @post_ram_clear: pointer to platform post ram-clear function.
+ */
+struct ds1685_priv {
+	struct rtc_device *dev;
+	void __iomem *regs;
+	u32 regstep;
+	resource_size_t baseaddr;
+	size_t size;
+	spinlock_t lock;
+	struct work_struct work;
+	int irq_num;
+	bool bcd_mode;
+	bool no_irq;
+	bool uie_unsupported;
+	bool alloc_io_resources;
+	u8 (*read)(struct ds1685_priv *, int);
+	void (*write)(struct ds1685_priv *, int, u8);
+	void (*prepare_poweroff)(void);
+	void (*wake_alarm)(void);
+	void (*post_ram_clear)(void);
+};
+
+
+/**
+ * struct ds1685_rtc_platform_data - platform data structure.
+ * @plat_prepare_poweroff: platform-specific pre-poweroff function.
+ * @plat_wake_alarm: platform-specific wake alarm function.
+ * @plat_post_ram_clear: platform-specific post ram-clear function.
+ *
+ * If your platform needs to use a custom padding/step size between
+ * registers, or uses one or more of the extended interrupts and needs special
+ * handling, then include this header file in your platform definition and
+ * set regstep and the plat_* pointers as appropriate.
+ */
+struct ds1685_rtc_platform_data {
+	const u32 regstep;
+	const bool bcd_mode;
+	const bool no_irq;
+	const bool uie_unsupported;
+	const bool alloc_io_resources;
+	u8 (*plat_read)(struct ds1685_priv *, int);
+	void (*plat_write)(struct ds1685_priv *, int, u8);
+	void (*plat_prepare_poweroff)(void);
+	void (*plat_wake_alarm)(void);
+	void (*plat_post_ram_clear)(void);
+};
+
+
+/*
+ * Time Registers.
+ */
+#define RTC_SECS		0x00	/* Seconds 00-59 */
+#define RTC_SECS_ALARM		0x01	/* Alarm Seconds 00-59 */
+#define RTC_MINS		0x02	/* Minutes 00-59 */
+#define RTC_MINS_ALARM		0x03	/* Alarm Minutes 00-59 */
+#define RTC_HRS			0x04	/* Hours 01-12 AM/PM || 00-23 */
+#define RTC_HRS_ALARM		0x05	/* Alarm Hours 01-12 AM/PM || 00-23 */
+#define RTC_WDAY		0x06	/* Day of Week 01-07 */
+#define RTC_MDAY		0x07	/* Day of Month 01-31 */
+#define RTC_MONTH		0x08	/* Month 01-12 */
+#define RTC_YEAR		0x09	/* Year 00-99 */
+#define RTC_CENTURY		0x48	/* Century 00-99 */
+#define RTC_MDAY_ALARM		0x49	/* Alarm Day of Month 01-31 */
+
+
+/*
+ * Bit masks for the Time registers in BCD Mode (DM = 0).
+ */
+#define RTC_SECS_BCD_MASK	0x7f	/* - x x x x x x x */
+#define RTC_MINS_BCD_MASK	0x7f	/* - x x x x x x x */
+#define RTC_HRS_12_BCD_MASK	0x1f	/* - - - x x x x x */
+#define RTC_HRS_24_BCD_MASK	0x3f	/* - - x x x x x x */
+#define RTC_MDAY_BCD_MASK	0x3f	/* - - x x x x x x */
+#define RTC_MONTH_BCD_MASK	0x1f	/* - - - x x x x x */
+#define RTC_YEAR_BCD_MASK	0xff	/* x x x x x x x x */
+
+/*
+ * Bit masks for the Time registers in BIN Mode (DM = 1).
+ */
+#define RTC_SECS_BIN_MASK	0x3f	/* - - x x x x x x */
+#define RTC_MINS_BIN_MASK	0x3f	/* - - x x x x x x */
+#define RTC_HRS_12_BIN_MASK	0x0f	/* - - - - x x x x */
+#define RTC_HRS_24_BIN_MASK	0x1f	/* - - - x x x x x */
+#define RTC_MDAY_BIN_MASK	0x1f	/* - - - x x x x x */
+#define RTC_MONTH_BIN_MASK	0x0f	/* - - - - x x x x */
+#define RTC_YEAR_BIN_MASK	0x7f	/* - x x x x x x x */
+
+/*
+ * Bit masks common for the Time registers in BCD or BIN Mode.
+ */
+#define RTC_WDAY_MASK		0x07	/* - - - - - x x x */
+#define RTC_CENTURY_MASK	0xff	/* x x x x x x x x */
+#define RTC_MDAY_ALARM_MASK	0xff	/* x x x x x x x x */
+#define RTC_HRS_AMPM_MASK	BIT(7)	/* Mask for the AM/PM bit */
+
+
+
+/*
+ * Control Registers.
+ */
+#define RTC_CTRL_A		0x0a	/* Control Register A */
+#define RTC_CTRL_B		0x0b	/* Control Register B */
+#define RTC_CTRL_C		0x0c	/* Control Register C */
+#define RTC_CTRL_D		0x0d	/* Control Register D */
+#define RTC_EXT_CTRL_4A		0x4a	/* Extended Control Register 4A */
+#define RTC_EXT_CTRL_4B		0x4b	/* Extended Control Register 4B */
+
+
+/*
+ * Bit names in Control Register A.
+ */
+#define RTC_CTRL_A_UIP		BIT(7)	/* Update In Progress */
+#define RTC_CTRL_A_DV2		BIT(6)	/* Countdown Chain */
+#define RTC_CTRL_A_DV1		BIT(5)	/* Oscillator Enable */
+#define RTC_CTRL_A_DV0		BIT(4)	/* Bank Select */
+#define RTC_CTRL_A_RS2		BIT(2)	/* Rate-Selection Bit 2 */
+#define RTC_CTRL_A_RS3		BIT(3)	/* Rate-Selection Bit 3 */
+#define RTC_CTRL_A_RS1		BIT(1)	/* Rate-Selection Bit 1 */
+#define RTC_CTRL_A_RS0		BIT(0)	/* Rate-Selection Bit 0 */
+#define RTC_CTRL_A_RS_MASK	0x0f	/* RS3 + RS2 + RS1 + RS0 */
+
+/*
+ * Bit names in Control Register B.
+ */
+#define RTC_CTRL_B_SET		BIT(7)	/* SET Bit */
+#define RTC_CTRL_B_PIE		BIT(6)	/* Periodic-Interrupt Enable */
+#define RTC_CTRL_B_AIE		BIT(5)	/* Alarm-Interrupt Enable */
+#define RTC_CTRL_B_UIE		BIT(4)	/* Update-Ended Interrupt-Enable */
+#define RTC_CTRL_B_SQWE		BIT(3)	/* Square-Wave Enable */
+#define RTC_CTRL_B_DM		BIT(2)	/* Data Mode */
+#define RTC_CTRL_B_2412		BIT(1)	/* 12-Hr/24-Hr Mode */
+#define RTC_CTRL_B_DSE		BIT(0)	/* Daylight Savings Enable */
+#define RTC_CTRL_B_PAU_MASK	0x70	/* PIE + AIE + UIE */
+
+
+/*
+ * Bit names in Control Register C.
+ *
+ * BIT(0), BIT(1), BIT(2), & BIT(3) are unused, always return 0, and cannot
+ * be written to.
+ */
+#define RTC_CTRL_C_IRQF		BIT(7)	/* Interrupt-Request Flag */
+#define RTC_CTRL_C_PF		BIT(6)	/* Periodic-Interrupt Flag */
+#define RTC_CTRL_C_AF		BIT(5)	/* Alarm-Interrupt Flag */
+#define RTC_CTRL_C_UF		BIT(4)	/* Update-Ended Interrupt Flag */
+#define RTC_CTRL_C_PAU_MASK	0x70	/* PF + AF + UF */
+
+
+/*
+ * Bit names in Control Register D.
+ *
+ * BIT(0) through BIT(6) are unused, always return 0, and cannot
+ * be written to.
+ */
+#define RTC_CTRL_D_VRT		BIT(7)	/* Valid RAM and Time */
+
+
+/*
+ * Bit names in Extended Control Register 4A.
+ *
+ * On the DS1685/DS1687/DS1689/DS1693, BIT(4) and BIT(5) are reserved for
+ * future use.  They can be read from and written to, but have no effect
+ * on the RTC's operation.
+ *
+ * On the DS17x85/DS17x87, BIT(5) is Burst-Mode Enable (BME), and allows
+ * access to the extended NV-SRAM by automatically incrementing the address
+ * register when they are read from or written to.
+ */
+#define RTC_CTRL_4A_VRT2	BIT(7)	/* Auxillary Battery Status */
+#define RTC_CTRL_4A_INCR	BIT(6)	/* Increment-in-Progress Status */
+#define RTC_CTRL_4A_PAB		BIT(3)	/* Power-Active Bar Control */
+#define RTC_CTRL_4A_RF		BIT(2)	/* RAM-Clear Flag */
+#define RTC_CTRL_4A_WF		BIT(1)	/* Wake-Up Alarm Flag */
+#define RTC_CTRL_4A_KF		BIT(0)	/* Kickstart Flag */
+#if !defined(CONFIG_RTC_DRV_DS1685) && !defined(CONFIG_RTC_DRV_DS1689)
+#define RTC_CTRL_4A_BME		BIT(5)	/* Burst-Mode Enable */
+#endif
+#define RTC_CTRL_4A_RWK_MASK	0x07	/* RF + WF + KF */
+
+
+/*
+ * Bit names in Extended Control Register 4B.
+ */
+#define RTC_CTRL_4B_ABE		BIT(7)	/* Auxillary Battery Enable */
+#define RTC_CTRL_4B_E32K	BIT(6)	/* Enable 32.768Hz on SQW Pin */
+#define RTC_CTRL_4B_CS		BIT(5)	/* Crystal Select */
+#define RTC_CTRL_4B_RCE		BIT(4)	/* RAM Clear-Enable */
+#define RTC_CTRL_4B_PRS		BIT(3)	/* PAB Reset-Select */
+#define RTC_CTRL_4B_RIE		BIT(2)	/* RAM Clear-Interrupt Enable */
+#define RTC_CTRL_4B_WIE		BIT(1)	/* Wake-Up Alarm-Interrupt Enable */
+#define RTC_CTRL_4B_KSE		BIT(0)	/* Kickstart Interrupt-Enable */
+#define RTC_CTRL_4B_RWK_MASK	0x07	/* RIE + WIE + KSE */
+
+
+/*
+ * Misc register names in Bank 1.
+ *
+ * The DV0 bit in Control Register A must be set to 1 for these registers
+ * to become available, including Extended Control Registers 4A & 4B.
+ */
+#define RTC_BANK1_SSN_MODEL	0x40	/* Model Number */
+#define RTC_BANK1_SSN_BYTE_1	0x41	/* 1st Byte of Serial Number */
+#define RTC_BANK1_SSN_BYTE_2	0x42	/* 2nd Byte of Serial Number */
+#define RTC_BANK1_SSN_BYTE_3	0x43	/* 3rd Byte of Serial Number */
+#define RTC_BANK1_SSN_BYTE_4	0x44	/* 4th Byte of Serial Number */
+#define RTC_BANK1_SSN_BYTE_5	0x45	/* 5th Byte of Serial Number */
+#define RTC_BANK1_SSN_BYTE_6	0x46	/* 6th Byte of Serial Number */
+#define RTC_BANK1_SSN_CRC	0x47	/* Serial CRC Byte */
+#define RTC_BANK1_RAM_DATA_PORT	0x53	/* Extended RAM Data Port */
+
+
+/*
+ * Model-specific registers in Bank 1.
+ *
+ * The addresses below differ depending on the model of the RTC chip
+ * selected in the kernel configuration.  Not all of these features are
+ * supported in the main driver at present.
+ *
+ * DS1685/DS1687   - Extended NV-SRAM address (LSB only).
+ * DS1689/DS1693   - Vcc, Vbat, Pwr Cycle Counters & Customer-specific S/N.
+ * DS17x85/DS17x87 - Extended NV-SRAM addresses (MSB & LSB) & Write counter.
+ */
+#if defined(CONFIG_RTC_DRV_DS1685)
+#define RTC_BANK1_RAM_ADDR	0x50	/* NV-SRAM Addr */
+#elif defined(CONFIG_RTC_DRV_DS1689)
+#define RTC_BANK1_VCC_CTR_LSB	0x54	/* Vcc Counter Addr (LSB) */
+#define RTC_BANK1_VCC_CTR_MSB	0x57	/* Vcc Counter Addr (MSB) */
+#define RTC_BANK1_VBAT_CTR_LSB	0x58	/* Vbat Counter Addr (LSB) */
+#define RTC_BANK1_VBAT_CTR_MSB	0x5b	/* Vbat Counter Addr (MSB) */
+#define RTC_BANK1_PWR_CTR_LSB	0x5c	/* Pwr Cycle Counter Addr (LSB) */
+#define RTC_BANK1_PWR_CTR_MSB	0x5d	/* Pwr Cycle Counter Addr (MSB) */
+#define RTC_BANK1_UNIQ_SN	0x60	/* Customer-specific S/N */
+#else /* DS17x85/DS17x87 */
+#define RTC_BANK1_RAM_ADDR_LSB	0x50	/* NV-SRAM Addr (LSB) */
+#define RTC_BANK1_RAM_ADDR_MSB	0x51	/* NV-SRAM Addr (MSB) */
+#define RTC_BANK1_WRITE_CTR	0x5e	/* RTC Write Counter */
+#endif
+
+
+/*
+ * Model numbers.
+ *
+ * The DS1688/DS1691 and DS1689/DS1693 chips share the same model number
+ * and the manual doesn't indicate any major differences.  As such, they
+ * are regarded as the same chip in this driver.
+ */
+#define RTC_MODEL_DS1685	0x71	/* DS1685/DS1687 */
+#define RTC_MODEL_DS17285	0x72	/* DS17285/DS17287 */
+#define RTC_MODEL_DS1689	0x73	/* DS1688/DS1691/DS1689/DS1693 */
+#define RTC_MODEL_DS17485	0x74	/* DS17485/DS17487 */
+#define RTC_MODEL_DS17885	0x78	/* DS17885/DS17887 */
+
+
+/*
+ * Periodic Interrupt Rates / Square-Wave Output Frequency
+ *
+ * Periodic rates are selected by setting the RS3-RS0 bits in Control
+ * Register A and enabled via either the E32K bit in Extended Control
+ * Register 4B or the SQWE bit in Control Register B.
+ *
+ * E32K overrides the settings of RS3-RS0 and outputs a frequency of 32768Hz
+ * on the SQW pin of the RTC chip.  While there are 16 possible selections,
+ * the 1-of-16 decoder is only able to divide the base 32768Hz signal into 13
+ * smaller frequencies.  The values 0x01 and 0x02 are not used and are
+ * synonymous with 0x08 and 0x09, respectively.
+ *
+ * When E32K is set to a logic 1, periodic interrupts are disabled and reading
+ * /dev/rtc will return -EINVAL.  This also applies if the periodic interrupt
+ * frequency is set to 0Hz.
+ *
+ * Not currently used by the rtc-ds1685 driver because the RTC core removed
+ * support for hardware-generated periodic-interrupts in favour of
+ * hrtimer-generated interrupts.  But these defines are kept around for use
+ * in userland, as documentation to the hardware, and possible future use if
+ * hardware-generated periodic interrupts are ever added back.
+ */
+					/* E32K RS3 RS2 RS1 RS0 */
+#define RTC_SQW_8192HZ		0x03	/*  0    0   0   1   1  */
+#define RTC_SQW_4096HZ		0x04	/*  0    0   1   0   0  */
+#define RTC_SQW_2048HZ		0x05	/*  0    0   1   0   1  */
+#define RTC_SQW_1024HZ		0x06	/*  0    0   1   1   0  */
+#define RTC_SQW_512HZ		0x07	/*  0    0   1   1   1  */
+#define RTC_SQW_256HZ		0x08	/*  0    1   0   0   0  */
+#define RTC_SQW_128HZ		0x09	/*  0    1   0   0   1  */
+#define RTC_SQW_64HZ		0x0a	/*  0    1   0   1   0  */
+#define RTC_SQW_32HZ		0x0b	/*  0    1   0   1   1  */
+#define RTC_SQW_16HZ		0x0c	/*  0    1   1   0   0  */
+#define RTC_SQW_8HZ		0x0d	/*  0    1   1   0   1  */
+#define RTC_SQW_4HZ		0x0e	/*  0    1   1   1   0  */
+#define RTC_SQW_2HZ		0x0f	/*  0    1   1   1   1  */
+#define RTC_SQW_0HZ		0x00	/*  0    0   0   0   0  */
+#define RTC_SQW_32768HZ		32768	/*  1    -   -   -   -  */
+#define RTC_MAX_USER_FREQ	8192
+
+
+/*
+ * NVRAM data & addresses:
+ *   - 50 bytes of NVRAM are available just past the clock registers.
+ *   - 64 additional bytes are available in Bank0.
+ *
+ * Extended, battery-backed NV-SRAM:
+ *   - DS1685/DS1687    - 128 bytes.
+ *   - DS1689/DS1693    - 0 bytes.
+ *   - DS17285/DS17287  - 2048 bytes.
+ *   - DS17485/DS17487  - 4096 bytes.
+ *   - DS17885/DS17887  - 8192 bytes.
+ */
+#define NVRAM_TIME_BASE		0x0e	/* NVRAM Addr in Time regs */
+#define NVRAM_BANK0_BASE	0x40	/* NVRAM Addr in Bank0 regs */
+#define NVRAM_SZ_TIME		50
+#define NVRAM_SZ_BANK0		64
+#if defined(CONFIG_RTC_DRV_DS1685)
+#  define NVRAM_SZ_EXTND	128
+#elif defined(CONFIG_RTC_DRV_DS1689)
+#  define NVRAM_SZ_EXTND	0
+#elif defined(CONFIG_RTC_DRV_DS17285)
+#  define NVRAM_SZ_EXTND	2048
+#elif defined(CONFIG_RTC_DRV_DS17485)
+#  define NVRAM_SZ_EXTND	4096
+#elif defined(CONFIG_RTC_DRV_DS17885)
+#  define NVRAM_SZ_EXTND	8192
+#endif
+#define NVRAM_TOTAL_SZ_BANK0	(NVRAM_SZ_TIME + NVRAM_SZ_BANK0)
+#define NVRAM_TOTAL_SZ		(NVRAM_TOTAL_SZ_BANK0 + NVRAM_SZ_EXTND)
+
+
+/*
+ * Function Prototypes.
+ */
+extern void __noreturn
+ds1685_rtc_poweroff(struct platform_device *pdev);
+
+#endif /* _LINUX_RTC_DS1685_H_ */