From: Sascha Hauer <s.hauer@pengutronix.de>

This driver provides a I2C bus driver for the CGEB interface
found on some Congatec x86 modules. No devices are registered
on the bus, the user has to do this via the i2c device /sys
interface.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Mary Strodl <mstrodl@csh.rit.edu>
---
 drivers/i2c/busses/Kconfig             |   7 +
 drivers/i2c/busses/Makefile            |   1 +
 drivers/i2c/busses/i2c-congatec-cgeb.c | 189 +++++++++++++++++++++++++
 3 files changed, 197 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-congatec-cgeb.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index fe6e8a1bb607..504a0be54f04 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1261,6 +1261,13 @@ config I2C_RCAR
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-rcar.
 
+config I2C_CONGATEC_CGEB
+	tristate "Congatec CGEB I2C driver"
+	depends on MFD_CONGATEC_CGEB
+	help
+	  This driver provides support for the I2C busses accssable via
+	  the Congatec CGEB interface found on Congatec boards.
+
 comment "External I2C/SMBus adapter drivers"
 
 config I2C_DIOLAN_U2C
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 78d0561339e5..f4e9fa7542be 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -128,6 +128,7 @@ obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 obj-$(CONFIG_I2C_GXP)		+= i2c-gxp.o
+obj-$(CONFIG_I2C_CONGATEC_CGEB)	+= i2c-congatec-cgeb.o
 
 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
diff --git a/drivers/i2c/busses/i2c-congatec-cgeb.c b/drivers/i2c/busses/i2c-congatec-cgeb.c
new file mode 100644
index 000000000000..5afee15ebdb3
--- /dev/null
+++ b/drivers/i2c/busses/i2c-congatec-cgeb.c
@@ -0,0 +1,189 @@
+/*
+ * CGEB i2c driver
+ *
+ * (c) 2011 Sascha Hauer, Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/i2c.h>
+#include <linux/mfd/congatec-cgeb.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define CG_I2C_FLAG_START   0x00080    /* send START condition */
+#define CG_I2C_FLAG_STOP    0x00040    /* send STOP condition */
+#define CG_I2C_FLAG_ALL_ACK 0x08000    /* send ACK on all read bytes */
+#define CG_I2C_FLAG_ALL_NAK 0x04000    /* send NAK on all read bytes */
+
+struct cgeb_i2c_priv {
+	struct cgeb_board_data *board;
+	struct i2c_adapter adapter;
+	int unit;
+};
+
+static u32 cgeb_i2c_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static int cgeb_i2c_set_speed(struct cgeb_i2c_priv *priv, int speed)
+{
+	struct cgeb_function_parameters fps;
+
+	memset(&fps, 0, sizeof(fps));
+
+	fps.unit = priv->unit;
+	fps.pars[0] = speed;
+
+	return cgeb_call(priv->board, &fps, CgebI2CSetFrequency);
+}
+
+static int cgeb_i2c_xfer(struct i2c_adapter *adapter,
+		struct i2c_msg *msgs, int num)
+{
+	struct cgeb_function_parameters fps;
+	int i, ret;
+	unsigned long flags = CG_I2C_FLAG_START;
+	struct cgeb_i2c_priv *priv = i2c_get_adapdata(adapter);
+	unsigned long rdlen, wrlen;
+	unsigned char *rdbuf, *wrbuf, *raw_wrbuf;
+	unsigned short lmax = 0;
+
+	/*
+	 * With cgeb the I2C address is part of the write data
+	 * buffer, so allocate a buffer with the length of the
+	 * longest write buffer + 1
+	 */
+	for (i = 0; i < num; i++)
+		if (!(msgs[i].flags & I2C_M_RD))
+			lmax = max(lmax, msgs[i].len);
+
+	raw_wrbuf = kmalloc(lmax + 1, GFP_KERNEL);
+	if (!raw_wrbuf)
+		return -ENOMEM;
+
+	for (i = 0; i < num; i++) {
+		if (msgs[i].flags & I2C_M_RD) {
+			rdbuf = msgs[i].buf;
+			rdlen = msgs[i].len;
+			wrbuf = NULL;
+			wrlen = 0;
+		} else {
+			rdbuf = NULL;
+			rdlen = 0;
+			wrbuf = msgs[i].buf;
+			wrlen = msgs[i].len;
+		}
+
+		raw_wrbuf[0] = msgs[i].addr << 1;
+		if (wrlen)
+			memcpy(&raw_wrbuf[1], wrbuf, wrlen);
+
+		if (msgs[i].flags & I2C_M_RD)
+			raw_wrbuf[0] |= 1;
+
+		if (i == num - 1)
+			flags |= CG_I2C_FLAG_STOP;
+
+		dev_dbg(&adapter->dev,
+				"%s: rd: %p/%ld wr: %p/%ld flags: 0x%08lx %s\n",
+				__func__, rdbuf, rdlen, raw_wrbuf, wrlen + 1,
+				flags,
+				msgs[i].flags & I2C_M_RD ? "READ" : "WRITE");
+
+		memset(&fps, 0, sizeof(fps));
+
+		fps.unit = priv->unit;
+		fps.pars[0] = wrlen + 1;
+		fps.pars[1] = rdlen;
+		fps.pars[2] = flags;
+		fps.iptr = raw_wrbuf;
+		fps.optr = rdbuf;
+		fps.optr_size = sizeof(*rdbuf) * rdlen;
+		fps.iptr_size = (wrlen + 1) * sizeof(*raw_wrbuf);
+
+		ret = cgeb_call(priv->board, &fps, CgebI2CTransfer);
+		if (ret) {
+			ret = -EREMOTEIO;
+			goto out;
+		}
+	}
+
+	ret = num;
+
+out:
+	kfree(raw_wrbuf);
+
+	return ret;
+}
+
+static struct i2c_algorithm cgeb_i2c_algo = {
+	.master_xfer    = cgeb_i2c_xfer,
+	.functionality  = cgeb_i2c_func,
+};
+
+static int cgeb_i2c_probe(struct platform_device *pdev)
+{
+	struct cgeb_i2c_priv *priv;
+	struct cgeb_pdata *pdata = pdev->dev.platform_data;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	strcpy(priv->adapter.name, pdev->name);
+	priv->adapter.owner             = THIS_MODULE;
+	priv->adapter.algo              = &cgeb_i2c_algo;
+	priv->adapter.dev.parent        = &pdev->dev;
+	priv->unit = pdata->unit;
+	priv->board = pdata->board;
+	i2c_set_adapdata(&priv->adapter, priv);
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = cgeb_i2c_set_speed(priv, 400000);
+	if (ret)
+		/* not a critical error, we can continue with the default speed. */
+		dev_warn(&pdev->dev, "Could not set speed to 400KHz\n");
+
+	ret = i2c_add_adapter(&priv->adapter);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "registration failed\n");
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "registered\n");
+
+	return 0;
+};
+
+static int cgeb_i2c_remove(struct platform_device *pdev)
+{
+	struct cgeb_i2c_priv *priv = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&priv->adapter);
+
+	return 0;
+}
+
+static struct platform_driver cgeb_i2c_driver = {
+	.probe          = cgeb_i2c_probe,
+	.remove         = cgeb_i2c_remove,
+	.driver = {
+		.name   = "cgeb-i2c",
+	},
+};
+module_platform_driver(cgeb_i2c_driver);
+
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
+MODULE_DESCRIPTION("cgeb i2c driver");
+MODULE_LICENSE("GPL");
-- 
2.45.2

Hi Mary,

On Thu, Aug 01, 2024 at 12:06:10PM GMT, Mary Strodl wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> This driver provides a I2C bus driver for the CGEB interface
> found on some Congatec x86 modules. No devices are registered
> on the bus, the user has to do this via the i2c device /sys
> interface.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
> Signed-off-by: Mary Strodl <mstrodl@csh.rit.edu>
> ---
>  drivers/i2c/busses/Kconfig             |   7 +
>  drivers/i2c/busses/Makefile            |   1 +
>  drivers/i2c/busses/i2c-congatec-cgeb.c | 189 +++++++++++++++++++++++++
>  3 files changed, 197 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-congatec-cgeb.c

Thanks for your patch, doesn't look bad.

However, I'm going to ask to please run checkpatch.pl fix the
suggested output and resend it.

Thanks,
Andi

On Thu, Aug 08, 2024 at 12:21:24AM +0100, Andi Shyti wrote:
> However, I'm going to ask to please run checkpatch.pl fix the
> suggested output and resend it.

Thanks for taking a look! I didn't know about checkpatch and
sparse before now, so I appreciate the messages :)

I sent a new version (v3) that should address the feedback.