[PATCH 3/3] i2c: Add Congatec CGEB I2C driver

Mary Strodl
2024-07-18T01:25:21Z

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 | 187 +++++++++++++++++++++++++
3 files changed, 195 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..decaef30ca0a
--- /dev/null
+++ b/drivers/i2c/busses/i2c-congatec-cgeb.c
@@ -0,0 +1,187 @@
+/*
+ * 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;
+
+ 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