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 000000000000..e6337a56d741
--- /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_ */