1 files changed, 392 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-au1550.c b/drivers/i2c/busses/i2c-au1550.c
new file mode 100644
index 000000000..22aed9225
--- /dev/null
+++ b/drivers/i2c/busses/i2c-au1550.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
+ * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
+ *
+ * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
+ *
+ * The documentation describes this as an SMBus controller, but it doesn't
+ * understand any of the SMBus protocol in hardware.  It's really an I2C
+ * controller that could emulate most of the SMBus in software.
+ *
+ * This is just a skeleton adapter to use with the Au1550 PSC
+ * algorithm.  It was developed for the Pb1550, but will work with
+ * any Au1550 board that has a similar PSC configuration.
+ */
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+
+#include <asm/mach-au1x00/au1000.h>
+#include <asm/mach-au1x00/au1xxx_psc.h>
+
+#define PSC_SEL		0x00
+#define PSC_CTRL	0x04
+#define PSC_SMBCFG	0x08
+#define PSC_SMBMSK	0x0C
+#define PSC_SMBPCR	0x10
+#define PSC_SMBSTAT	0x14
+#define PSC_SMBEVNT	0x18
+#define PSC_SMBTXRX	0x1C
+#define PSC_SMBTMR	0x20
+
+struct i2c_au1550_data {
+	void __iomem *psc_base;
+	int	xfer_timeout;
+	struct i2c_adapter adap;
+};
+
+static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
+{
+	__raw_writel(v, a->psc_base + r);
+	wmb();
+}
+
+static inline unsigned long RD(struct i2c_au1550_data *a, int r)
+{
+	return __raw_readl(a->psc_base + r);
+}
+
+static int wait_xfer_done(struct i2c_au1550_data *adap)
+{
+	int i;
+
+	/* Wait for Tx Buffer Empty */
+	for (i = 0; i < adap->xfer_timeout; i++) {
+		if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
+			return 0;
+
+		udelay(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int wait_ack(struct i2c_au1550_data *adap)
+{
+	unsigned long stat;
+
+	if (wait_xfer_done(adap))
+		return -ETIMEDOUT;
+
+	stat = RD(adap, PSC_SMBEVNT);
+	if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int wait_master_done(struct i2c_au1550_data *adap)
+{
+	int i;
+
+	/* Wait for Master Done. */
+	for (i = 0; i < 2 * adap->xfer_timeout; i++) {
+		if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
+			return 0;
+		udelay(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int
+do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
+{
+	unsigned long stat;
+
+	/* Reset the FIFOs, clear events. */
+	stat = RD(adap, PSC_SMBSTAT);
+	WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);
+
+	if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
+		WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
+		while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
+			cpu_relax();
+		udelay(50);
+	}
+
+	/* Write out the i2c chip address and specify operation */
+	addr <<= 1;
+	if (rd)
+		addr |= 1;
+
+	/* zero-byte xfers stop immediately */
+	if (q)
+		addr |= PSC_SMBTXRX_STP;
+
+	/* Put byte into fifo, start up master. */
+	WR(adap, PSC_SMBTXRX, addr);
+	WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
+	if (wait_ack(adap))
+		return -EIO;
+	return (q) ? wait_master_done(adap) : 0;
+}
+
+static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
+{
+	int j;
+
+	if (wait_xfer_done(adap))
+		return -EIO;
+
+	j =  adap->xfer_timeout * 100;
+	do {
+		j--;
+		if (j <= 0)
+			return -EIO;
+
+		if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
+			j = 0;
+		else
+			udelay(1);
+	} while (j > 0);
+
+	*out = RD(adap, PSC_SMBTXRX);
+
+	return 0;
+}
+
+static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
+		    unsigned int len)
+{
+	int i;
+
+	if (len == 0)
+		return 0;
+
+	/* A read is performed by stuffing the transmit fifo with
+	 * zero bytes for timing, waiting for bytes to appear in the
+	 * receive fifo, then reading the bytes.
+	 */
+	i = 0;
+	while (i < (len - 1)) {
+		WR(adap, PSC_SMBTXRX, 0);
+		if (wait_for_rx_byte(adap, &buf[i]))
+			return -EIO;
+
+		i++;
+	}
+
+	/* The last byte has to indicate transfer done. */
+	WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
+	if (wait_master_done(adap))
+		return -EIO;
+
+	buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
+	return 0;
+}
+
+static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
+		     unsigned int len)
+{
+	int i;
+	unsigned long data;
+
+	if (len == 0)
+		return 0;
+
+	i = 0;
+	while (i < (len-1)) {
+		data = buf[i];
+		WR(adap, PSC_SMBTXRX, data);
+		if (wait_ack(adap))
+			return -EIO;
+		i++;
+	}
+
+	/* The last byte has to indicate transfer done. */
+	data = buf[i];
+	data |= PSC_SMBTXRX_STP;
+	WR(adap, PSC_SMBTXRX, data);
+	if (wait_master_done(adap))
+		return -EIO;
+	return 0;
+}
+
+static int
+au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
+{
+	struct i2c_au1550_data *adap = i2c_adap->algo_data;
+	struct i2c_msg *p;
+	int i, err = 0;
+
+	WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);
+
+	for (i = 0; !err && i < num; i++) {
+		p = &msgs[i];
+		err = do_address(adap, p->addr, p->flags & I2C_M_RD,
+				 (p->len == 0));
+		if (err || !p->len)
+			continue;
+		if (p->flags & I2C_M_RD)
+			err = i2c_read(adap, p->buf, p->len);
+		else
+			err = i2c_write(adap, p->buf, p->len);
+	}
+
+	/* Return the number of messages processed, or the error code.
+	*/
+	if (err == 0)
+		err = num;
+
+	WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);
+
+	return err;
+}
+
+static u32 au1550_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm au1550_algo = {
+	.master_xfer	= au1550_xfer,
+	.functionality	= au1550_func,
+};
+
+static void i2c_au1550_setup(struct i2c_au1550_data *priv)
+{
+	unsigned long cfg;
+
+	WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
+	WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
+	WR(priv, PSC_SMBCFG, 0);
+	WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
+	while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
+		cpu_relax();
+
+	cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
+	WR(priv, PSC_SMBCFG, cfg);
+
+	/* Divide by 8 to get a 6.25 MHz clock.  The later protocol
+	 * timings are based on this clock.
+	 */
+	cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
+	WR(priv, PSC_SMBCFG, cfg);
+	WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);
+
+	/* Set the protocol timer values.  See Table 71 in the
+	 * Au1550 Data Book for standard timing values.
+	 */
+	WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(20) | \
+		PSC_SMBTMR_SET_PU(20) | PSC_SMBTMR_SET_SH(20) | \
+		PSC_SMBTMR_SET_SU(20) | PSC_SMBTMR_SET_CL(20) | \
+		PSC_SMBTMR_SET_CH(20));
+
+	cfg |= PSC_SMBCFG_DE_ENABLE;
+	WR(priv, PSC_SMBCFG, cfg);
+	while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
+		cpu_relax();
+
+	WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
+}
+
+static void i2c_au1550_disable(struct i2c_au1550_data *priv)
+{
+	WR(priv, PSC_SMBCFG, 0);
+	WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
+}
+
+/*
+ * registering functions to load algorithms at runtime
+ * Prior to calling us, the 50MHz clock frequency and routing
+ * must have been set up for the PSC indicated by the adapter.
+ */
+static int
+i2c_au1550_probe(struct platform_device *pdev)
+{
+	struct i2c_au1550_data *priv;
+	struct resource *r;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(struct i2c_au1550_data),
+			    GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->psc_base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(priv->psc_base))
+		return PTR_ERR(priv->psc_base);
+
+	priv->xfer_timeout = 200;
+
+	priv->adap.nr = pdev->id;
+	priv->adap.algo = &au1550_algo;
+	priv->adap.algo_data = priv;
+	priv->adap.dev.parent = &pdev->dev;
+	strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
+
+	/* Now, set up the PSC for SMBus PIO mode. */
+	i2c_au1550_setup(priv);
+
+	ret = i2c_add_numbered_adapter(&priv->adap);
+	if (ret) {
+		i2c_au1550_disable(priv);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, priv);
+	return 0;
+}
+
+static int i2c_au1550_remove(struct platform_device *pdev)
+{
+	struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&priv->adap);
+	i2c_au1550_disable(priv);
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int i2c_au1550_suspend(struct device *dev)
+{
+	struct i2c_au1550_data *priv = dev_get_drvdata(dev);
+
+	i2c_au1550_disable(priv);
+
+	return 0;
+}
+
+static int i2c_au1550_resume(struct device *dev)
+{
+	struct i2c_au1550_data *priv = dev_get_drvdata(dev);
+
+	i2c_au1550_setup(priv);
+
+	return 0;
+}
+
+static const struct dev_pm_ops i2c_au1550_pmops = {
+	.suspend	= i2c_au1550_suspend,
+	.resume		= i2c_au1550_resume,
+};
+
+#define AU1XPSC_SMBUS_PMOPS (&i2c_au1550_pmops)
+
+#else
+#define AU1XPSC_SMBUS_PMOPS NULL
+#endif
+
+static struct platform_driver au1xpsc_smbus_driver = {
+	.driver = {
+		.name	= "au1xpsc_smbus",
+		.pm	= AU1XPSC_SMBUS_PMOPS,
+	},
+	.probe		= i2c_au1550_probe,
+	.remove		= i2c_au1550_remove,
+};
+
+module_platform_driver(au1xpsc_smbus_driver);
+
+MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
+MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:au1xpsc_smbus");