rtc: isl12026: new driver.

The ISL12026 is a combination RTC and EEPROM device with I2C
interface.  The standard RTC driver interface is provided.  The EEPROM
is accessed via the NVMEM interface.
Reviewed-by: NRob Herring <robh@kernel.org>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/isil,isl12026.txt

+ISL12026 I2C RTC/EEPROM
+
+ISL12026 is an I2C RTC/EEPROM combination device.  The RTC and control
+registers respond at bus address 0x6f, and the EEPROM array responds
+at bus address 0x57.  The canonical "reg" value will be for the RTC portion.
+
+Required properties supported by the device:
+
+ - "compatible": must be "isil,isl12026"
+ - "reg": I2C bus address of the device (always 0x6f)
+
+Optional properties:
+
+ - "isil,pwr-bsw": If present PWR.BSW bit must be set to the specified
+                   value for proper operation.
+
+ - "isil,pwr-sbib": If present PWR.SBIB bit must be set to the specified
+                    value for proper operation.
+
+
+Example:
+
+	rtc@6f {
+		compatible = "isil,isl12026";
+		reg = <0x6f>;
+		isil,pwr-bsw = <0>;
+		isil,pwr-sbib = <1>;
+	}

drivers/rtc/Kconfig

@@ -407,6 +407,16 @@ config RTC_DRV_ISL12022
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-isl12022.
 
+config RTC_DRV_ISL12026
+	tristate "Intersil ISL12026"
+	depends on OF || COMPILE_TEST
+	help
+	  If you say yes here you get support for the
+	  Intersil ISL12026 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-isl12026.
+
 config RTC_DRV_X1205
 	tristate "Xicor/Intersil X1205"
 	help

drivers/rtc/Makefile

@@ -76,6 +76,7 @@ obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
 obj-$(CONFIG_RTC_DRV_HYM8563)	+= rtc-hym8563.o
 obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
+obj-$(CONFIG_RTC_DRV_ISL12026)	+= rtc-isl12026.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_LP8788)	+= rtc-lp8788.o

drivers/rtc/rtc-isl12026.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * An I2C driver for the Intersil ISL 12026
+ *
+ * Copyright (c) 2018 Cavium, Inc.
+ */
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+/* register offsets */
+#define ISL12026_REG_PWR	0x14
+# define ISL12026_REG_PWR_BSW	BIT(6)
+# define ISL12026_REG_PWR_SBIB	BIT(7)
+#define ISL12026_REG_SC		0x30
+#define ISL12026_REG_HR		0x32
+# define ISL12026_REG_HR_MIL	BIT(7)	/* military or 24 hour time */
+#define ISL12026_REG_SR		0x3f
+# define ISL12026_REG_SR_RTCF	BIT(0)
+# define ISL12026_REG_SR_WEL	BIT(1)
+# define ISL12026_REG_SR_RWEL	BIT(2)
+# define ISL12026_REG_SR_MBZ	BIT(3)
+# define ISL12026_REG_SR_OSCF	BIT(4)
+
+/* The EEPROM array responds at i2c address 0x57 */
+#define ISL12026_EEPROM_ADDR	0x57
+
+#define ISL12026_PAGESIZE 16
+#define ISL12026_NVMEM_WRITE_TIME 20
+
+struct isl12026 {
+	struct rtc_device *rtc;
+	struct i2c_client *nvm_client;
+};
+
+static int isl12026_read_reg(struct i2c_client *client, int reg)
+{
+	u8 addr[] = {0, reg};
+	u8 val;
+	int ret;
+
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= sizeof(addr),
+			.buf	= addr
+		}, {
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= 1,
+			.buf	= &val
+		}
+	};
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "read reg error, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+	} else {
+		ret = val;
+	}
+
+	return ret;
+}
+
+static int isl12026_arm_write(struct i2c_client *client)
+{
+	int ret;
+	u8 op[3];
+	struct i2c_msg msg = {
+		.addr	= client->addr,
+		.flags	= 0,
+		.len	= 1,
+		.buf	= op
+	};
+
+	/* Set SR.WEL */
+	op[0] = 0;
+	op[1] = ISL12026_REG_SR;
+	op[2] = ISL12026_REG_SR_WEL;
+	msg.len = 3;
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev, "write error SR.WEL, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	}
+
+	/* Set SR.WEL and SR.RWEL */
+	op[2] = ISL12026_REG_SR_WEL | ISL12026_REG_SR_RWEL;
+	msg.len = 3;
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev,
+			"write error SR.WEL|SR.RWEL, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	} else {
+		ret = 0;
+	}
+out:
+	return ret;
+}
+
+static int isl12026_disarm_write(struct i2c_client *client)
+{
+	int ret;
+	u8 op[3] = {0, ISL12026_REG_SR, 0};
+	struct i2c_msg msg = {
+		.addr	= client->addr,
+		.flags	= 0,
+		.len	= sizeof(op),
+		.buf	= op
+	};
+
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev,
+			"write error SR, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+	} else {
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static int isl12026_write_reg(struct i2c_client *client, int reg, u8 val)
+{
+	int ret;
+	u8 op[3] = {0, reg, val};
+	struct i2c_msg msg = {
+		.addr	= client->addr,
+		.flags	= 0,
+		.len	= sizeof(op),
+		.buf	= op
+	};
+
+	ret = isl12026_arm_write(client);
+	if (ret)
+		return ret;
+
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	}
+
+	msleep(ISL12026_NVMEM_WRITE_TIME);
+
+	ret = isl12026_disarm_write(client);
+out:
+	return ret;
+}
+
+static int isl12026_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int ret;
+	u8 op[10];
+	struct i2c_msg msg = {
+		.addr	= client->addr,
+		.flags	= 0,
+		.len	= sizeof(op),
+		.buf	= op
+	};
+
+	ret = isl12026_arm_write(client);
+	if (ret)
+		return ret;
+
+	/* Set the CCR registers */
+	op[0] = 0;
+	op[1] = ISL12026_REG_SC;
+	op[2] = bin2bcd(tm->tm_sec); /* SC */
+	op[3] = bin2bcd(tm->tm_min); /* MN */
+	op[4] = bin2bcd(tm->tm_hour) | ISL12026_REG_HR_MIL; /* HR */
+	op[5] = bin2bcd(tm->tm_mday); /* DT */
+	op[6] = bin2bcd(tm->tm_mon + 1); /* MO */
+	op[7] = bin2bcd(tm->tm_year % 100); /* YR */
+	op[8] = bin2bcd(tm->tm_wday & 7); /* DW */
+	op[9] = bin2bcd(tm->tm_year >= 100 ? 20 : 19); /* Y2K */
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	}
+
+	ret = isl12026_disarm_write(client);
+out:
+	return ret;
+}
+
+static int isl12026_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	u8 ccr[8];
+	u8 addr[2];
+	u8 sr;
+	int ret;
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= sizeof(addr),
+			.buf	= addr
+		}, {
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+		}
+	};
+
+	/* First, read SR */
+	addr[0] = 0;
+	addr[1] = ISL12026_REG_SR;
+	msgs[1].len = 1;
+	msgs[1].buf = &sr;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "read error, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	}
+
+	if (sr & ISL12026_REG_SR_RTCF)
+		dev_warn(&client->dev, "Real-Time Clock Failure on read\n");
+	if (sr & ISL12026_REG_SR_OSCF)
+		dev_warn(&client->dev, "Oscillator Failure on read\n");
+
+	/* Second, CCR regs */
+	addr[0] = 0;
+	addr[1] = ISL12026_REG_SC;
+	msgs[1].len = sizeof(ccr);
+	msgs[1].buf = ccr;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "read error, ret=%d\n", ret);
+		ret = ret < 0 ? ret : -EIO;
+		goto out;
+	}
+
+	tm->tm_sec = bcd2bin(ccr[0] & 0x7F);
+	tm->tm_min = bcd2bin(ccr[1] & 0x7F);
+	if (ccr[2] & ISL12026_REG_HR_MIL)
+		tm->tm_hour = bcd2bin(ccr[2] & 0x3F);
+	else
+		tm->tm_hour = bcd2bin(ccr[2] & 0x1F) +
+			((ccr[2] & 0x20) ? 12 : 0);
+	tm->tm_mday = bcd2bin(ccr[3] & 0x3F);
+	tm->tm_mon = bcd2bin(ccr[4] & 0x1F) - 1;
+	tm->tm_year = bcd2bin(ccr[5]);
+	if (bcd2bin(ccr[7]) == 20)
+		tm->tm_year += 100;
+	tm->tm_wday = ccr[6] & 0x07;
+
+	ret = 0;
+out:
+	return ret;
+}
+
+static const struct rtc_class_ops isl12026_rtc_ops = {
+	.read_time	= isl12026_rtc_read_time,
+	.set_time	= isl12026_rtc_set_time,
+};
+
+static int isl12026_nvm_read(void *p, unsigned int offset,
+			     void *val, size_t bytes)
+{
+	struct isl12026 *priv = p;
+	int ret;
+	u8 addr[2];
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= priv->nvm_client->addr,
+			.flags	= 0,
+			.len	= sizeof(addr),
+			.buf	= addr
+		}, {
+			.addr	= priv->nvm_client->addr,
+			.flags	= I2C_M_RD,
+			.buf	= val
+		}
+	};
+
+	/*
+	 * offset and bytes checked and limited by nvmem core, so
+	 * proceed without further checks.
+	 */
+	ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
+	if (ret)
+		return ret;
+
+	/* 2 bytes of address, most significant first */
+	addr[0] = offset >> 8;
+	addr[1] = offset;
+	msgs[1].len = bytes;
+	ret = i2c_transfer(priv->nvm_client->adapter, msgs, ARRAY_SIZE(msgs));
+
+	mutex_unlock(&priv->rtc->ops_lock);
+
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&priv->nvm_client->dev,
+			"nvmem read error, ret=%d\n", ret);
+		return ret < 0 ? ret : -EIO;
+	}
+
+	return 0;
+}
+
+static int isl12026_nvm_write(void *p, unsigned int offset,
+			      void *val, size_t bytes)
+{
+	struct isl12026 *priv = p;
+	int ret;
+	u8 *v = val;
+	size_t chunk_size, num_written;
+	u8 payload[ISL12026_PAGESIZE + 2]; /* page + 2 address bytes */
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= priv->nvm_client->addr,
+			.flags	= 0,
+			.buf	= payload
+		}
+	};
+
+	/*
+	 * offset and bytes checked and limited by nvmem core, so
+	 * proceed without further checks.
+	 */
+	ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
+	if (ret)
+		return ret;
+
+	num_written = 0;
+	while (bytes) {
+		chunk_size = round_down(offset, ISL12026_PAGESIZE) +
+			ISL12026_PAGESIZE - offset;
+		chunk_size = min(bytes, chunk_size);
+		/*
+		 * 2 bytes of address, most significant first, followed
+		 * by page data bytes
+		 */
+		memcpy(payload + 2, v + num_written, chunk_size);
+		payload[0] = offset >> 8;
+		payload[1] = offset;
+		msgs[0].len = chunk_size + 2;
+		ret = i2c_transfer(priv->nvm_client->adapter,
+				   msgs, ARRAY_SIZE(msgs));
+		if (ret != ARRAY_SIZE(msgs)) {
+			dev_err(&priv->nvm_client->dev,
+				"nvmem write error, ret=%d\n", ret);
+			ret = ret < 0 ? ret : -EIO;
+			break;
+		}
+		ret = 0;
+		bytes -= chunk_size;
+		offset += chunk_size;
+		num_written += chunk_size;
+		msleep(ISL12026_NVMEM_WRITE_TIME);
+	}
+
+	mutex_unlock(&priv->rtc->ops_lock);
+
+	return ret;
+}
+
+static void isl12026_force_power_modes(struct i2c_client *client)
+{
+	int ret;
+	int pwr, requested_pwr;
+	u32 bsw_val, sbib_val;
+	bool set_bsw, set_sbib;
+
+	/*
+	 * If we can read the of_property, set the specified value.
+	 * If there is an error reading the of_property (likely
+	 * because it does not exist), keep the current value.
+	 */
+	ret = of_property_read_u32(client->dev.of_node,
+				   "isil,pwr-bsw", &bsw_val);
+	set_bsw = (ret == 0);
+
+	ret = of_property_read_u32(client->dev.of_node,
+				   "isil,pwr-sbib", &sbib_val);
+	set_sbib = (ret == 0);
+
+	/* Check if PWR.BSW and/or PWR.SBIB need specified values */
+	if (!set_bsw && !set_sbib)
+		return;
+
+	pwr = isl12026_read_reg(client, ISL12026_REG_PWR);
+	if (pwr < 0) {
+		dev_warn(&client->dev, "Error: Failed to read PWR %d\n", pwr);
+		return;
+	}
+
+	requested_pwr = pwr;
+
+	if (set_bsw) {
+		if (bsw_val)
+			requested_pwr |= ISL12026_REG_PWR_BSW;
+		else
+			requested_pwr &= ~ISL12026_REG_PWR_BSW;
+	} /* else keep current BSW */
+
+	if (set_sbib) {
+		if (sbib_val)
+			requested_pwr |= ISL12026_REG_PWR_SBIB;
+		else
+			requested_pwr &= ~ISL12026_REG_PWR_SBIB;
+	} /* else keep current SBIB */
+
+	if (pwr >= 0 && pwr != requested_pwr) {
+		dev_dbg(&client->dev, "PWR: %02x\n", pwr);
+		dev_dbg(&client->dev, "Updating PWR to: %02x\n", requested_pwr);
+		isl12026_write_reg(client, ISL12026_REG_PWR, requested_pwr);
+	}
+}
+
+static int isl12026_probe_new(struct i2c_client *client)
+{
+	struct isl12026 *priv;
+	int ret;
+	struct nvmem_config nvm_cfg;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, priv);
+
+	isl12026_force_power_modes(client);
+
+	priv->nvm_client = i2c_new_dummy(client->adapter, ISL12026_EEPROM_ADDR);
+	if (!priv->nvm_client)
+		return -ENOMEM;
+
+	priv->rtc = devm_rtc_allocate_device(&client->dev);
+	ret = PTR_ERR_OR_ZERO(priv->rtc);
+	if (ret)
+		return ret;
+
+	priv->rtc->ops = &isl12026_rtc_ops;
+	priv->rtc->nvram_old_abi = false;
+	ret = rtc_register_device(priv->rtc);
+	if (ret)
+		return ret;
+
+	memset(&nvm_cfg, 0, sizeof(nvm_cfg));
+	nvm_cfg.name = "eeprom";
+	nvm_cfg.read_only = false;
+	nvm_cfg.root_only = true;
+	nvm_cfg.base_dev = &client->dev;
+	nvm_cfg.priv = priv;
+	nvm_cfg.stride = 1;
+	nvm_cfg.word_size = 1;
+	nvm_cfg.size = 512;
+	nvm_cfg.reg_read = isl12026_nvm_read;
+	nvm_cfg.reg_write = isl12026_nvm_write;
+
+	return rtc_nvmem_register(priv->rtc, &nvm_cfg);
+}
+
+static int isl12026_remove(struct i2c_client *client)
+{
+	struct isl12026 *priv = i2c_get_clientdata(client);
+
+	i2c_unregister_device(priv->nvm_client);
+	return 0;
+}
+
+static const struct of_device_id isl12026_dt_match[] = {
+	{ .compatible = "isil,isl12026" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, isl12026_dt_match);
+
+static struct i2c_driver isl12026_driver = {
+	.driver		= {
+		.name	= "rtc-isl12026",
+		.of_match_table = isl12026_dt_match,
+	},
+	.probe_new	= isl12026_probe_new,
+	.remove		= isl12026_remove,
+};
+
+module_i2c_driver(isl12026_driver);
+
+MODULE_DESCRIPTION("ISL 12026 RTC driver");
+MODULE_LICENSE("GPL");