i2c: add nexell driver

Changes in relation to FriendlyARM's U-Boot nanopi2-v2016.01:
- i2c/nx_i2c.c: Some adaptions mainly because of changes in
  "struct udevice".
- several Bugfixes in nx_i2c.c.
- the driver has been for s5p6818 only. Code extended appropriately
  in order s5p4418 is also working.
- "probe_chip" added.
- pinctrl-driver/dt is used instead of configuring the i2c I/O-pins
  in the i2c-driver.
- '#ifdef CONFIG...' changed to 'if (IS_ENABLED(CONFIG...))' where
  possible (and similar).
- livetree API (dev_read_...) is used instead of fdt one (fdt...).

Signed-off-by: Stefan Bosch <stefan_b@posteo.net>

3 files changed, 636 insertions, 0 deletions

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 87d11b663c..dec6dc9dfa 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -333,6 +333,15 @@ config SYS_MXC_I2C8_SLAVE
 	 MXC I2C8 Slave
 endif
 
+config SYS_I2C_NEXELL
+	bool "Nexell I2C driver"
+	depends on DM_I2C
+	help
+	  Add support for the Nexell I2C driver. This is used with various
+	  Nexell parts such as S5Pxx18 series SoCs. All chips
+	  have several I2C ports and all are provided, controlled by the
+	  device tree.
+
 config SYS_I2C_OMAP24XX
 	bool "TI OMAP2+ I2C driver"
 	depends on ARCH_OMAP2PLUS || ARCH_K3
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 174081e252..e851ec462e 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SYS_I2C_LPC32XX) += lpc32xx_i2c.o
 obj-$(CONFIG_SYS_I2C_MESON) += meson_i2c.o
 obj-$(CONFIG_SYS_I2C_MVTWSI) += mvtwsi.o
 obj-$(CONFIG_SYS_I2C_MXC) += mxc_i2c.o
+obj-$(CONFIG_SYS_I2C_NEXELL) += nx_i2c.o
 obj-$(CONFIG_SYS_I2C_OCTEON) += octeon_i2c.o
 obj-$(CONFIG_SYS_I2C_OMAP24XX) += omap24xx_i2c.o
 obj-$(CONFIG_SYS_I2C_RCAR_I2C) += rcar_i2c.o
diff --git a/drivers/i2c/nx_i2c.c b/drivers/i2c/nx_i2c.c
new file mode 100644
index 0000000000..ca14a0ecac
--- /dev/null
+++ b/drivers/i2c/nx_i2c.c
@@ -0,0 +1,626 @@
+#include <common.h>
+#include <errno.h>
+#include <dm.h>
+#include <i2c.h>
+#include <log.h>
+#include <asm/arch/nexell.h>
+#include <asm/arch/reset.h>
+#include <asm/arch/clk.h>
+#include <asm/arch/nx_gpio.h>
+#include <linux/delay.h>
+
+#define I2C_WRITE       0
+#define I2C_READ        1
+
+#define I2CSTAT_MTM     0xC0    /* Master Transmit Mode */
+#define I2CSTAT_MRM     0x80    /* Master Receive Mode */
+#define I2CSTAT_BSY     0x20    /* Read: Bus Busy */
+#define I2CSTAT_SS      0x20    /* Write: START (1) / STOP (0) */
+#define I2CSTAT_RXTXEN  0x10    /* Rx/Tx enable */
+#define I2CSTAT_ABT	0x08	/* Arbitration bit */
+#define I2CSTAT_NACK    0x01    /* Nack bit */
+#define I2CCON_IRCLR    0x100   /* Interrupt Clear bit  */
+#define I2CCON_ACKGEN   0x80    /* Acknowledge generation */
+#define I2CCON_TCP256	0x40    /* Tx-clock prescaler: 16 (0) / 256 (1) */
+#define I2CCON_IRENB	0x20	/* Interrupt Enable bit  */
+#define I2CCON_IRPND    0x10    /* Interrupt pending bit */
+#define I2CCON_TCDMSK	0x0F    /* I2C-bus transmit clock divider bit mask */
+
+#ifdef CONFIG_ARCH_S5P6818
+#define SDADLY_CLKSTEP	5	/* SDA delay: Reg. val. is multiple of 5 clks */
+#define SDADLY_MAX	3	/* SDA delay: Max. reg. value is 3 */
+#define I2CLC_FILTER	0x04	/* SDA filter on */
+#else
+#define STOPCON_CLR	0x01	/* Clock Line Release */
+#define STOPCON_DLR	0x02	/* Data Line Release */
+#define STOPCON_NAG	0x04	/* not-ackn. generation and data shift cont. */
+#endif
+
+#define I2C_TIMEOUT_MS	10      /* 10 ms */
+
+#define I2C_M_NOSTOP	0x100
+
+#define MAX_I2C_NUM 3
+
+#define DEFAULT_SPEED   100000  /* default I2C speed [Hz] */
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct nx_i2c_regs {
+	uint     iiccon;
+	uint     iicstat;
+	uint     iicadd;
+	uint     iicds;
+#ifdef CONFIG_ARCH_S5P6818
+	/* S5P6818: Offset 0x10 is Line Control Register (SDA-delay, Filter) */
+	uint     iiclc;
+#else
+	/* S5P4418: Offset 0x10 is Stop Control Register */
+	uint     iicstopcon;
+#endif
+};
+
+struct nx_i2c_bus {
+	uint bus_num;
+	struct nx_i2c_regs *regs;
+	uint speed;
+	uint target_speed;
+#ifdef CONFIG_ARCH_S5P6818
+	uint sda_delay;
+#else
+	/* setup time for Stop condition [us] */
+	uint tsu_stop;
+#endif
+};
+
+/* s5pxx18 i2c must be reset before enabled */
+static void i2c_reset(int ch)
+{
+	int rst_id = RESET_ID_I2C0 + ch;
+
+	nx_rstcon_setrst(rst_id, 0);
+	nx_rstcon_setrst(rst_id, 1);
+}
+
+static uint i2c_get_clkrate(struct nx_i2c_bus *bus)
+{
+	struct clk *clk;
+	int index = bus->bus_num;
+	char name[50] = {0, };
+
+	sprintf(name, "%s.%d", DEV_NAME_I2C, index);
+	clk = clk_get((const char *)name);
+	if (!clk)
+		return -1;
+
+	return clk_get_rate(clk);
+}
+
+static uint i2c_set_clk(struct nx_i2c_bus *bus, uint enb)
+{
+	struct clk *clk;
+	char name[50];
+
+	sprintf(name, "%s.%d", DEV_NAME_I2C, bus->bus_num);
+	clk = clk_get((const char *)name);
+	if (!clk) {
+		debug("%s(): clk_get(%s) error!\n",
+		      __func__, (const char *)name);
+		return -EINVAL;
+	}
+
+	clk_disable(clk);
+	if (enb)
+		clk_enable(clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_ARCH_S5P6818
+/* Set SDA line delay, not available at S5P4418 */
+static int nx_i2c_set_sda_delay(struct nx_i2c_bus *bus)
+{
+	struct nx_i2c_regs *i2c = bus->regs;
+	uint pclk = 0;
+	uint t_pclk = 0;
+	uint delay = 0;
+
+	/* get input clock of the I2C-controller */
+	pclk = i2c_get_clkrate(bus);
+
+	if (bus->sda_delay) {
+		/* t_pclk = period time of one pclk [ns] */
+		t_pclk = DIV_ROUND_UP(1000, pclk / 1000000);
+		/* delay = number of pclks required for sda_delay [ns] */
+		delay = DIV_ROUND_UP(bus->sda_delay, t_pclk);
+		/* delay = register value (step of 5 clocks) */
+		delay = DIV_ROUND_UP(delay, SDADLY_CLKSTEP);
+		/* max. possible register value = 3 */
+		if (delay > SDADLY_MAX) {
+			delay = SDADLY_MAX;
+			debug("%s(): sda-delay des.: %dns, sat. to max.: %dns (granularity: %dns)\n",
+			      __func__, bus->sda_delay, t_pclk * delay * SDADLY_CLKSTEP,
+			      t_pclk * SDADLY_CLKSTEP);
+		} else {
+			debug("%s(): sda-delay des.: %dns, act.: %dns (granularity: %dns)\n",
+			      __func__, bus->sda_delay, t_pclk * delay * SDADLY_CLKSTEP,
+			      t_pclk * SDADLY_CLKSTEP);
+		}
+
+		delay |= I2CLC_FILTER;
+	} else {
+		delay = 0;
+		debug("%s(): sda-delay = 0\n", __func__);
+	}
+
+	delay &= 0x7;
+	writel(delay, &i2c->iiclc);
+
+	return 0;
+}
+#endif
+
+static int nx_i2c_set_bus_speed(struct udevice *dev, uint speed)
+{
+	struct nx_i2c_bus *bus = dev_get_priv(dev);
+	struct nx_i2c_regs *i2c = bus->regs;
+	unsigned long pclk, pres = 16, div;
+
+	if (i2c_set_clk(bus, 1))
+		return -EINVAL;
+
+	/* get input clock of the I2C-controller */
+	pclk = i2c_get_clkrate(bus);
+
+	/* calculate prescaler and divisor values */
+	if ((pclk / pres / (16 + 1)) > speed)
+		/* prescaler value 16 is too less --> set to 256 */
+		pres = 256;
+
+	div = 0;
+	/* actual divider = div + 1 */
+	while ((pclk / pres / (div + 1)) > speed)
+		div++;
+
+	if (div > 0xF) {
+		debug("%s(): pres==%ld, div==0x%lx is saturated to 0xF !)\n",
+		      __func__, pres, div);
+		div = 0xF;
+	} else {
+		debug("%s(): pres==%ld, div==0x%lx)\n", __func__, pres, div);
+	}
+
+	/* set Tx-clock divisor and prescaler values */
+	writel((div & I2CCON_TCDMSK) | ((pres == 256) ? I2CCON_TCP256 : 0),
+	       &i2c->iiccon);
+
+	/* init to SLAVE REVEIVE and set slaveaddr */
+	writel(0, &i2c->iicstat);
+	writel(0x00, &i2c->iicadd);
+
+	/* program Master Transmit (and implicit STOP) */
+	writel(I2CSTAT_MTM | I2CSTAT_RXTXEN, &i2c->iicstat);
+
+	/* calculate actual I2C speed [Hz] */
+	bus->speed = pclk / ((div + 1) * pres);
+	debug("%s(): speed des.: %dHz, act.: %dHz\n",
+	      __func__, speed, bus->speed);
+
+#ifdef CONFIG_ARCH_S5P6818
+	nx_i2c_set_sda_delay(bus);
+#else
+	/* setup time for Stop condition [us], min. 4us @ 100kHz I2C-clock */
+	bus->tsu_stop = DIV_ROUND_UP(400, bus->speed / 1000);
+#endif
+
+	if (i2c_set_clk(bus, 0))
+		return -EINVAL;
+	return 0;
+}
+
+static void i2c_process_node(struct udevice *dev)
+{
+	struct nx_i2c_bus *bus = dev_get_priv(dev);
+
+	bus->target_speed = dev_read_s32_default(dev, "clock-frequency",
+						 DEFAULT_SPEED);
+#ifdef CONFIG_ARCH_S5P6818
+	bus->sda_delay = dev_read_s32_default(dev, "i2c-sda-delay-ns", 0);
+#endif
+}
+
+static int nx_i2c_probe(struct udevice *dev)
+{
+	struct nx_i2c_bus *bus = dev_get_priv(dev);
+	fdt_addr_t addr;
+
+	/* get regs = i2c base address */
+	addr = devfdt_get_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+	bus->regs = (struct nx_i2c_regs *)addr;
+
+	bus->bus_num = dev->seq;
+
+	/* i2c node parsing */
+	i2c_process_node(dev);
+	if (!bus->target_speed)
+		return -ENODEV;
+
+	/* reset */
+	i2c_reset(bus->bus_num);
+
+	return 0;
+}
+
+/* i2c bus busy check */
+static int i2c_is_busy(struct nx_i2c_regs *i2c)
+{
+	ulong start_time;
+
+	start_time = get_timer(0);
+	while (readl(&i2c->iicstat) & I2CSTAT_BSY) {
+		if (get_timer(start_time) > I2C_TIMEOUT_MS) {
+			debug("Timeout\n");
+			return -EBUSY;
+		}
+	}
+	return 0;
+}
+
+/* irq enable/disable functions */
+static void i2c_enable_irq(struct nx_i2c_regs *i2c)
+{
+	unsigned int reg;
+
+	reg = readl(&i2c->iiccon);
+	reg |= I2CCON_IRENB;
+	writel(reg, &i2c->iiccon);
+}
+
+/* irq clear function */
+static void i2c_clear_irq(struct nx_i2c_regs *i2c)
+{
+	unsigned int reg;
+
+	reg = readl(&i2c->iiccon);
+	/* reset interrupt pending flag */
+	reg &= ~(I2CCON_IRPND);
+	/*
+	 * Interrupt must also be cleared!
+	 * Otherwise linux boot may hang after:
+	 *     [    0.436000] NetLabel:  unlabeled traffic allowed by default
+	 * Next would be:
+	 *     [    0.442000] clocksource: Switched to clocksource source timer
+	 */
+	reg |= I2CCON_IRCLR;
+	writel(reg, &i2c->iiccon);
+}
+
+/* ack enable functions */
+static void i2c_enable_ack(struct nx_i2c_regs *i2c)
+{
+	unsigned int reg;
+
+	reg = readl(&i2c->iiccon);
+	reg |= I2CCON_ACKGEN;
+	writel(reg, &i2c->iiccon);
+}
+
+static void i2c_send_stop(struct nx_i2c_bus *bus)
+{
+	struct nx_i2c_regs *i2c = bus->regs;
+
+	if (IS_ENABLED(CONFIG_ARCH_S5P6818)) {
+		unsigned int reg;
+
+		reg = readl(&i2c->iicstat);
+		reg |= I2CSTAT_MRM | I2CSTAT_RXTXEN;
+		reg &= (~I2CSTAT_SS);
+
+		writel(reg, &i2c->iicstat);
+		i2c_clear_irq(i2c);
+	} else {  /* S5P4418 */
+		writel(STOPCON_NAG, &i2c->iicstopcon);
+
+		i2c_clear_irq(i2c);
+
+		/*
+		 * Clock Line Release --> SDC changes from Low to High and
+		 * SDA from High to Low
+		 */
+		writel(STOPCON_CLR, &i2c->iicstopcon);
+
+		/* Hold SDA Low (Setup Time for Stop condition) */
+		udelay(bus->tsu_stop);
+
+		i2c_clear_irq(i2c);
+
+		/* Master Receive Mode Stop --> SDA becomes High */
+		writel(I2CSTAT_MRM, &i2c->iicstat);
+	}
+}
+
+static int wait_for_xfer(struct nx_i2c_regs *i2c)
+{
+	unsigned long start_time = get_timer(0);
+
+	do {
+		if (readl(&i2c->iiccon) & I2CCON_IRPND)
+			/* return -EREMOTEIO if not Acknowledged, otherwise 0 */
+			return (readl(&i2c->iicstat) & I2CSTAT_NACK) ?
+				-EREMOTEIO : 0;
+	} while (get_timer(start_time) < I2C_TIMEOUT_MS);
+
+	return -ETIMEDOUT;
+}
+
+static int i2c_transfer(struct nx_i2c_regs *i2c,
+			uchar cmd_type,
+			uchar chip_addr,
+			uchar addr[],
+			uchar addr_len,
+			uchar data[],
+			unsigned short data_len,
+			uint seq)
+{
+	uint status;
+	int i = 0, result;
+
+	/* Note: data_len = 0 is supported for "probe_chip" */
+
+	i2c_enable_irq(i2c);
+	i2c_enable_ack(i2c);
+
+	/* Get the slave chip address going */
+	/* Enable Rx/Tx */
+	writel(I2CSTAT_RXTXEN, &i2c->iicstat);
+
+	writel(chip_addr, &i2c->iicds);
+	status = I2CSTAT_RXTXEN | I2CSTAT_SS;
+	if (cmd_type == I2C_WRITE || (addr && addr_len))
+		status |= I2CSTAT_MTM;
+	else
+		status |= I2CSTAT_MRM;
+
+	writel(status, &i2c->iicstat);
+	if (seq)
+		i2c_clear_irq(i2c);
+
+	/* Wait for chip address to transmit. */
+	result = wait_for_xfer(i2c);
+	if (result) {
+		debug("%s: transmitting chip address failed\n", __func__);
+		goto bailout;
+	}
+
+	/* If register address needs to be transmitted - do it now. */
+	if (addr && addr_len) {  /* register addr */
+		while ((i < addr_len) && !result) {
+			writel(addr[i++], &i2c->iicds);
+			i2c_clear_irq(i2c);
+			result = wait_for_xfer(i2c);
+		}
+
+		i = 0;
+		if (result) {
+			debug("%s: transmitting register address failed\n",
+			      __func__);
+			goto bailout;
+		}
+	}
+
+	switch (cmd_type) {
+	case I2C_WRITE:
+		while ((i < data_len) && !result) {
+			writel(data[i++], &i2c->iicds);
+			i2c_clear_irq(i2c);
+			result = wait_for_xfer(i2c);
+		}
+		break;
+	case I2C_READ:
+		if (addr && addr_len) {
+			/*
+			 * Register address has been sent, now send slave chip
+			 * address again to start the actual read transaction.
+			 */
+			writel(chip_addr, &i2c->iicds);
+
+			/* Generate a re-START. */
+			writel(I2CSTAT_MRM | I2CSTAT_RXTXEN |
+			       I2CSTAT_SS, &i2c->iicstat);
+			i2c_clear_irq(i2c);
+			result = wait_for_xfer(i2c);
+			if (result) {
+				debug("%s: I2C_READ: sending chip addr. failed\n",
+				      __func__);
+				goto bailout;
+			}
+		}
+
+		while ((i < data_len) && !result) {
+			/* disable ACK for final READ */
+			if (i == data_len - 1)
+				clrbits_le32(&i2c->iiccon, I2CCON_ACKGEN);
+
+			i2c_clear_irq(i2c);
+			result = wait_for_xfer(i2c);
+			data[i++] = readb(&i2c->iicds);
+		}
+
+		if (result == -EREMOTEIO)
+			 /* Not Acknowledged --> normal terminated read. */
+			result = 0;
+		else if (result == -ETIMEDOUT)
+			debug("%s: I2C_READ: time out\n", __func__);
+		else
+			debug("%s: I2C_READ: read not terminated with NACK\n",
+			      __func__);
+		break;
+
+	default:
+		debug("%s: bad call\n", __func__);
+		result = -EINVAL;
+		break;
+	}
+
+bailout:
+	return result;
+}
+
+static int nx_i2c_read(struct udevice *dev, uchar chip_addr, uint addr,
+		       uint alen, uchar *buffer, uint len, uint seq)
+{
+	struct nx_i2c_bus *i2c;
+	uchar xaddr[4];
+	int ret;
+
+	i2c = dev_get_priv(dev);
+	if (!i2c)
+		return -EFAULT;
+
+	if (alen > 4) {
+		debug("I2C read: addr len %d not supported\n", alen);
+		return -EADDRNOTAVAIL;
+	}
+
+	if (alen > 0)
+		xaddr[0] = (addr >> 24) & 0xFF;
+
+	if (alen > 0) {
+		xaddr[0] = (addr >> 24) & 0xFF;
+		xaddr[1] = (addr >> 16) & 0xFF;
+		xaddr[2] = (addr >> 8) & 0xFF;
+		xaddr[3] = addr & 0xFF;
+	}
+
+	ret = i2c_transfer(i2c->regs, I2C_READ, chip_addr << 1,
+			   &xaddr[4 - alen], alen, buffer, len, seq);
+
+	if (ret) {
+		debug("I2C read failed %d\n", ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int nx_i2c_write(struct udevice *dev, uchar chip_addr, uint addr,
+			uint alen, uchar *buffer, uint len, uint seq)
+{
+	struct nx_i2c_bus *i2c;
+	uchar xaddr[4];
+	int ret;
+
+	i2c = dev_get_priv(dev);
+	if (!i2c)
+		return -EFAULT;
+
+	if (alen > 4) {
+		debug("I2C write: addr len %d not supported\n", alen);
+		return -EINVAL;
+	}
+
+	if (alen > 0) {
+		xaddr[0] = (addr >> 24) & 0xFF;
+		xaddr[1] = (addr >> 16) & 0xFF;
+		xaddr[2] = (addr >> 8) & 0xFF;
+		xaddr[3] = addr & 0xFF;
+	}
+
+	ret = i2c_transfer(i2c->regs, I2C_WRITE, chip_addr << 1,
+			   &xaddr[4 - alen], alen, buffer, len, seq);
+	if (ret) {
+		debug("I2C write failed %d\n", ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int nx_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
+{
+	struct nx_i2c_bus *bus = dev_get_priv(dev);
+	struct nx_i2c_regs *i2c = bus->regs;
+	int ret;
+	int i;
+
+	/* The power loss by the clock, only during on/off. */
+	ret = i2c_set_clk(bus, 1);
+
+	if (!ret)
+		/* Bus State(Busy) check  */
+		ret = i2c_is_busy(i2c);
+	if (!ret) {
+		for (i = 0; i < nmsgs; msg++, i++) {
+			if (msg->flags & I2C_M_RD) {
+				ret = nx_i2c_read(dev, msg->addr, 0, 0,
+						  msg->buf, msg->len, i);
+			} else {
+				ret = nx_i2c_write(dev, msg->addr, 0, 0,
+						   msg->buf, msg->len, i);
+			}
+
+			if (ret) {
+				debug("i2c_xfer: error sending\n");
+				ret = -EREMOTEIO;
+			}
+		}
+
+		i2c_send_stop(bus);
+		if (i2c_set_clk(bus, 0))
+			ret = -EINVAL;
+	}
+
+	return ret;
+};
+
+static int nx_i2c_probe_chip(struct udevice *dev, u32 chip_addr,
+			     u32 chip_flags)
+{
+	int ret;
+	struct nx_i2c_bus *bus = dev_get_priv(dev);
+
+	ret = i2c_set_clk(bus, 1);
+
+	if (!ret) {
+		/*
+		 * Send Chip Address only
+		 * --> I2C transfer with data length and address length = 0.
+		 * If there is a Slave, i2c_transfer() returns 0 (acknowledge
+		 * transfer).
+		 * I2C_WRITE must be used in order Master Transmit Mode is
+		 * selected. Otherwise (in Master Receive Mode, I2C_READ)
+		 * sending the stop condition below is not working (SDA does
+		 * not transit to High).
+		 */
+		ret = i2c_transfer(bus->regs, I2C_WRITE, (uchar)chip_addr << 1,
+				   NULL, 0, NULL, 0, 0);
+
+		i2c_send_stop(bus);
+		if (i2c_set_clk(bus, 0))
+			ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static const struct dm_i2c_ops nx_i2c_ops = {
+	.xfer		= nx_i2c_xfer,
+	.probe_chip	= nx_i2c_probe_chip,
+	.set_bus_speed	= nx_i2c_set_bus_speed,
+};
+
+static const struct udevice_id nx_i2c_ids[] = {
+	{ .compatible = "nexell,s5pxx18-i2c" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_nexell) = {
+	.name		= "i2c_nexell",
+	.id		= UCLASS_I2C,
+	.of_match	= nx_i2c_ids,
+	.probe		= nx_i2c_probe,
+	.priv_auto_alloc_size	= sizeof(struct nx_i2c_bus),
+	.ops		= &nx_i2c_ops,
+};