[PATCH v2 2/2] i2c: add support for Zhaoxin I2C controller

Hans Hu
2023-08-14T08:41:19Z

Add Zhaoxin I2C controller driver. It provides the access to the i2c
busses, which connects to the touchpad, eeprom, etc.

Zhaoxin I2C controller provides two modes of operation:
FIFO mode: works in access requests without restart.
Byte mode: same IP with i2c-wmt and use driver i2c-viai2c-common.

Zhaoxin I2C controller has two separate busses, so may accommodate up
to two I2C adapters. Those adapters are listed in the ACPI namespace
with the "IIC1D17" HID, and probed by a platform driver.

The driver works with IRQ mode, and supports basic I2C features. Flags
I2C_AQ_NO_ZERO_LEN and I2C_AQ_COMB_WRITE_THEN_READ are used to limit
the unsupported access.

Signed-off-by: Hans Hu <hanshu-oc@zhaoxin.com>
---
MAINTAINERS | 7 +
drivers/i2c/busses/Kconfig | 11 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-viai2c-common.c | 12 +-
drivers/i2c/busses/i2c-viai2c-common.h | 11 +
drivers/i2c/busses/i2c-wmt.c | 2 +
drivers/i2c/busses/i2c-zhaoxin.c | 274 +++++++++++++++++++++++++
7 files changed, 315 insertions(+), 3 deletions(-)
create mode 100644 drivers/i2c/busses/i2c-zhaoxin.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b3648da1c5b2..bb65f7d748eb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9864,6 +9864,13 @@ L: linux-i2c@vger.kernel.org
F: Documentation/i2c/busses/i2c-ismt.rst
F: drivers/i2c/busses/i2c-ismt.c

+I2C/SMBUS ZHAOXIN DRIVER
+M: Hans Hu <hanshu@zhaoxin.com>
+L: linux-i2c@vger.kernel.org
+S: Maintained
+W: https://www.zhaoxin.com
+F: drivers/i2c/busses/i2c-zhaoxin.c
+
I2C/SMBUS STUB DRIVER
M: Jean Delvare <jdelvare@suse.com>
L: linux-i2c@vger.kernel.org
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b810030b21cd..4941093299b2 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -347,6 +347,17 @@ config I2C_SCMI
To compile this driver as a module, choose M here:
the module will be called i2c-scmi.

+config I2C_ZHAOXIN
+ tristate "Zhaoxin I2C Interface"
+ depends on PCI || COMPILE_TEST
+ select I2C_VIAI2C_COMMON
+ help
+ If you say yes to this option, support will be included for the
+ ZHAOXIN I2C interface
+
+ This driver can also be built as a module. If so, the module
+ will be called i2c-zhaoxin.
+
endif # ACPI

comment "Mac SMBus host controller drivers"
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index b7e20c3531b5..47bfab15b0a1 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_I2C_SIS630) += i2c-sis630.o
obj-$(CONFIG_I2C_SIS96X) += i2c-sis96x.o
obj-$(CONFIG_I2C_VIA) += i2c-via.o
obj-$(CONFIG_I2C_VIAPRO) += i2c-viapro.o
+obj-$(CONFIG_I2C_ZHAOXIN) += i2c-zhaoxin.o

# Mac SMBus host controller drivers
obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o
diff --git a/drivers/i2c/busses/i2c-viai2c-common.c b/drivers/i2c/busses/i2c-viai2c-common.c
index ffba29ce17c5..9d400ab10c25 100644
--- a/drivers/i2c/busses/i2c-viai2c-common.c
+++ b/drivers/i2c/busses/i2c-viai2c-common.c
@@ -53,7 +53,8 @@ static int via_i2c_write(struct via_i2c *i2c, struct i2c_msg *pmsg, int last)
writew(pmsg->buf[0], base + VIAI2C_CDR);
}

- if (!(pmsg->flags & I2C_M_NOSTART)) {
+ if (!(pmsg->flags & I2C_M_NOSTART)
+ && (i2c->platform & VIAI2C_PLAT_WMT)) {
val = readb(base + VIAI2C_CR);
val &= ~VIAI2C_CR_TX_END;
val |= VIAI2C_CR_CPU_RDY;
@@ -94,8 +95,10 @@ static int via_i2c_write(struct via_i2c *i2c, struct i2c_msg *pmsg, int last)
}

if (xfer_len == pmsg->len) {
- if (last != 1)
+ if (last != 1 && (i2c->platform & VIAI2C_PLAT_WMT))
writeb(VIAI2C_CR_ENABLE, base + VIAI2C_CR);
+ else if (last && (i2c->platform & VIAI2C_PLAT_ZHAOXIN))
+ writeb(VIAI2C_CR_TX_END, base + VIAI2C_CR);
} else {
writeb(pmsg->buf[xfer_len] & 0xFF, base + VIAI2C_CDR);
writeb(VIAI2C_CR_CONTINUE_MASK, base + VIAI2C_CR);
@@ -159,7 +162,8 @@ int via_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
for (i = 0; ret >= 0 && i < num; i++) {
struct i2c_msg * pmsg = &msgs[i];

- if (!(pmsg->flags & I2C_M_NOSTART)) {
+ if (!(pmsg->flags & I2C_M_NOSTART)
+ && (i2c->platform & VIAI2C_PLAT_WMT)) {
ret = via_i2c_wait_bus_ready(i2c);
if (ret < 0)
return ret;
@@ -181,6 +185,8 @@ static irqreturn_t via_i2c_isr(int irq, void *data)

/* save the status and write-clear it */
i2c->event = readw(i2c->base + VIAI2C_ISR);
+ if (!i2c->event)
+ return IRQ_NONE;
writew(i2c->event, i2c->base + VIAI2C_ISR);

complete(&i2c->complete);
diff --git a/drivers/i2c/busses/i2c-viai2c-common.h b/drivers/i2c/busses/i2c-viai2c-common.h
index f3a86f005eb9..c81018b440b2 100644
--- a/drivers/i2c/busses/i2c-viai2c-common.h
+++ b/drivers/i2c/busses/i2c-viai2c-common.h
@@ -46,6 +46,11 @@

#define VIAI2C_TIMEOUT (msecs_to_jiffies(1000))

+enum {
+ VIAI2C_PLAT_WMT,
+ VIAI2C_PLAT_ZHAOXIN
+};
+
struct via_i2c {
struct i2c_adapter adapter;
struct completion complete;
@@ -55,6 +60,12 @@ struct via_i2c {
int irq;
u16 event;
u16 tcr;
+ bool platform;
+ u16 tr;
+ u16 mcr;
+ u16 csr;
+ u8 fstp;
+ u8 hrv;
};

int via_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num);
diff --git a/drivers/i2c/busses/i2c-wmt.c b/drivers/i2c/busses/i2c-wmt.c
index d282f2146fb3..c9c3d27e8331 100644
--- a/drivers/i2c/busses/i2c-wmt.c
+++ b/drivers/i2c/busses/i2c-wmt.c
@@ -78,6 +78,8 @@ static int wmt_i2c_probe(struct platform_device *pdev)
if (err)
return err;

+ i2c_dev->platform = VIAI2C_PLAT_WMT;
+
i2c_dev->clk = of_clk_get(np, 0);
if (IS_ERR(i2c_dev->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(i2c_dev->clk),
diff --git a/drivers/i2c/busses/i2c-zhaoxin.c b/drivers/i2c/busses/i2c-zhaoxin.c
new file mode 100644
index 000000000000..73b10af9a7b9
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zhaoxin.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright(c) 2023 Shanghai Zhaoxin Semiconductor Corporation.
+ * All rights reserved.
+ */
+
+#include <linux/pci.h>
+#include "i2c-viai2c-common.h"
+
+#define ZXI2C_NAME "Zhaoxin-I2C"
+
+/*
+ * zhaoxin custom registers and bits
+ */
+/* reg CR Bit fields */
+#define ZXI2C_CR_FIFO_EN BIT(14)
+/* reg ISR Bit fields */
+#define ZXI2C_ISR_FIFO BIT(3)
+/* reg IMR Bit fields */
+#define ZXI2C_IMR_FIFO BIT(3)
+#define ZXI2C_IMR_FIFO_MASK (BIT(3) | VIAI2C_IMR_ADDRNACK)
+#define ZXI2C_IMR_BYTE_MASK (BIT(1) | VIAI2C_IMR_ADDRNACK)
+#define ZXI2C_CS 0x10
+#define ZXI2C_CS_CLK_50M BIT(0)
+#define ZXI2C_REV 0x11
+#define ZXI2C_HCR 0x12
+#define ZXI2C_HCR_FIFO_RST GENMASK(1, 0)
+#define ZXI2C_HTDR 0x13
+#define ZXI2C_HRDR 0x14
+#define ZXI2C_HTLR 0x15
+#define ZXI2C_HRLR 0x16
+#define ZXI2C_HWCNTR 0x18
+#define ZXI2C_HRCNTR 0x19
+
+/* parameters Constants */
+#define ZXI2C_GOLD_FSTP_100K 0xF3
+#define ZXI2C_GOLD_FSTP_400K 0x38
+#define ZXI2C_GOLD_FSTP_1M 0x13
+#define ZXI2C_GOLD_FSTP_3400K 0x37
+#define ZXI2C_HS_MASTER_CODE (0x08 << 8)
+
+#define ZXI2C_FIFO_SIZE 32
+
+#define zxi2c via_i2c
+
+static int zxi2c_fifo_xfer(struct zxi2c *i2c, struct i2c_msg *msg)
+{
+ int err;
+ u16 i, finished;
+ u16 tcr_val = i2c->tcr;
+ void __iomem *base = i2c->base;
+ int read = !!(msg->flags & I2C_M_RD);
+
+ /* reset fifo settings */
+ iowrite8(ZXI2C_HCR_FIFO_RST, base + ZXI2C_HCR);
+ /* select fifo mode */
+ iowrite16(ZXI2C_CR_FIFO_EN, i2c->base + VIAI2C_CR);
+ /* enable fifo interrupt */
+ iowrite8(ZXI2C_IMR_FIFO_MASK, base + VIAI2C_IMR);
+
+ /* sets the transmission length, direction, and the data to be sent */
+ if (read) {
+ tcr_val |= VIAI2C_TCR_READ;
+ iowrite8(msg->len - 1, base + ZXI2C_HRLR);
+ } else {
+
+ iowrite8(msg->len - 1, base + ZXI2C_HTLR);
+ for (i = 0; i < msg->len; i++)
+ iowrite8(msg->buf[i], base + ZXI2C_HTDR);
+ }
+ /* set slave addr */
+ tcr_val |= (msg->addr & VIAI2C_TCR_ADDR_MASK);
+
+ reinit_completion(&i2c->complete);
+
+ /* a write to the TCR triggers the transfer start */
+ iowrite16(tcr_val, i2c->base + VIAI2C_TCR);
+
+ err = via_i2c_wait_event(i2c, ZXI2C_ISR_FIFO);
+ if (err)
+ return err;
+
+ /* Gets the length and data that has been transferred */
+ if (read) {
+ finished = ioread8(base + ZXI2C_HRCNTR);
+ for (i = 0; i < finished; i++)
+ msg->buf[i] = ioread8(base + ZXI2C_HRDR);
+ } else {
+ finished = ioread8(base + ZXI2C_HWCNTR);
+ }
+
+ /* check if data NACK during transmitting */
+ if (finished != msg->len) {
+ dev_err(i2c->dev, "only %s %d/%d bytes\n",
+ read ? "read" : "write", finished, msg->len);
+ return -EAGAIN;
+ }
+
+ return 1;
+}
+
+static int zxi2c_byte_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ int err;
+ struct zxi2c *i2c = (struct zxi2c *)i2c_get_adapdata(adap);
+
+ /* select byte mode */
+ iowrite16(0, i2c->base + VIAI2C_CR);
+ /* enable interrupt */
+ iowrite8(ZXI2C_IMR_BYTE_MASK, i2c->base + VIAI2C_IMR);
+
+ err = via_i2c_xfer(adap, msgs, num);
+ /* kill unfinished transfer signal */
+ if (err < 0)
+ iowrite16(VIAI2C_CR_END_MASK, i2c->base + VIAI2C_CR);
+
+ return err;
+}
+
+static int zxi2c_master_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ int err;
+ struct zxi2c *i2c = (struct zxi2c *)i2c_get_adapdata(adap);
+
+ err = via_i2c_wait_bus_ready(i2c);
+ if (err)
+ return err;
+
+ if (num == 1 && msgs->len <= ZXI2C_FIFO_SIZE && msgs->len >= 2)
+ err = zxi2c_fifo_xfer(i2c, msgs);
+ else
+ err = zxi2c_byte_xfer(adap, msgs, num);
+ /*
+ * fifo or byte interrupts have been enabled inside the xfer functions.
+ * To make the code more concise, we put the disable action here
+ */
+ iowrite8(0, i2c->base + VIAI2C_IMR);
+ return err;
+}
+
+static u32 zxi2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm zxi2c_algorithm = {
+ .master_xfer = zxi2c_master_xfer,
+ .functionality = zxi2c_func,
+};
+
+static const struct i2c_adapter_quirks zxi2c_quirks = {
+ .flags = I2C_AQ_NO_ZERO_LEN | I2C_AQ_COMB_WRITE_THEN_READ,
+};
+
+static const u32 zxi2c_speed_params_table[][3] = {
+ /* speed, ZXI2C_TCR, ZXI2C_FSTP */
+ { I2C_MAX_STANDARD_MODE_FREQ, 0, ZXI2C_GOLD_FSTP_100K },
+ { I2C_MAX_FAST_MODE_FREQ, VIAI2C_TCR_FAST, ZXI2C_GOLD_FSTP_400K },
+ { I2C_MAX_FAST_MODE_PLUS_FREQ, VIAI2C_TCR_FAST, ZXI2C_GOLD_FSTP_1M },
+ { I2C_MAX_HIGH_SPEED_MODE_FREQ, VIAI2C_TCR_HS_MODE | VIAI2C_TCR_FAST,
+ ZXI2C_GOLD_FSTP_3400K },
+};
+
+static void zxi2c_set_bus_speed(struct zxi2c *i2c)
+{
+ iowrite16(i2c->tr, i2c->base + VIAI2C_TR);
+ iowrite8(ZXI2C_CS_CLK_50M, i2c->base + ZXI2C_CS);
+ iowrite16(i2c->mcr, i2c->base + VIAI2C_MCR);
+}
+
+static void zxi2c_get_bus_speed(struct zxi2c *i2c)
+{
+ u8 i, count;
+ u8 fstp;
+ const u32 *params;
+ u32 acpi_speed = i2c_acpi_find_bus_speed(i2c->dev);
+
+ count = ARRAY_SIZE(zxi2c_speed_params_table);
+ for (i = 0; i < count; i++)
+ if (acpi_speed == zxi2c_speed_params_table[i][0])
+ break;
+ /* if not found, use 400k as default */
+ i = i < count ? i : 1;
+
+ params = zxi2c_speed_params_table[i];
+ fstp = ioread8(i2c->base + VIAI2C_TR);
+ if (abs(fstp - params[2]) > 0x10) {
+ /*
+ * if BIOS setting value far from golden value,
+ * use golden value and warn user
+ */
+ dev_warn(i2c->dev, "speed:%d, fstp:0x%x, golden:0x%x\n",
+ params[0], fstp, params[2]);
+ i2c->tr = params[2] | 0xff00;
+ } else {
+ i2c->tr = fstp | 0xff00;
+ }
+
+ i2c->tcr = params[1];
+ i2c->mcr = ioread16(i2c->base + VIAI2C_MCR);
+ /* for Hs-mode, use 0000 1000 as master code */
+ if (params[0] == I2C_MAX_HIGH_SPEED_MODE_FREQ)
+ i2c->mcr |= ZXI2C_HS_MASTER_CODE;
+
+ dev_info(i2c->dev, "speed mode is %s\n",
+ i2c_freq_mode_string(params[0]));
+}
+
+static int zxi2c_probe(struct platform_device *pdev)
+{
+ int err = 0;
+ struct zxi2c *i2c;
+ struct pci_dev *pci;
+
+ err = via_i2c_init(pdev, &i2c);
+ if (err)
+ return err;
+
+ i2c->platform = VIAI2C_PLAT_ZHAOXIN;
+ i2c->hrv = ioread8(i2c->base + ZXI2C_REV);
+ i2c->csr = ioread16(i2c->base + VIAI2C_CSR);
+
+ zxi2c_get_bus_speed(i2c);
+ zxi2c_set_bus_speed(i2c);
+
+ i2c->adapter.owner = THIS_MODULE;
+ i2c->adapter.algo = &zxi2c_algorithm;
+ i2c->adapter.retries = 2;
+ i2c->adapter.quirks = &zxi2c_quirks;
+ i2c->adapter.dev.parent = &pdev->dev;
+ ACPI_COMPANION_SET(&i2c->adapter.dev, ACPI_COMPANION(&pdev->dev));
+ pci = to_pci_dev(pdev->dev.parent);
+ snprintf(i2c->adapter.name, sizeof(i2c->adapter.name), "%s-%s-%s",
+ ZXI2C_NAME, dev_name(&pci->dev), dev_name(i2c->dev));
+ i2c_set_adapdata(&i2c->adapter, i2c);
+
+ return devm_i2c_add_adapter(&pdev->dev, &i2c->adapter);
+}
+
+static int zxi2c_resume(struct device *dev)
+{
+ struct zxi2c *i2c = dev_get_drvdata(dev);
+
+ iowrite16(i2c->csr, i2c->base + VIAI2C_CSR);
+ zxi2c_set_bus_speed(i2c);
+
+ return 0;
+}
+
+static const struct dev_pm_ops zxi2c_pm = {
+ SET_SYSTEM_SLEEP_PM_OPS(NULL, zxi2c_resume)
+};
+
+static const struct acpi_device_id zxi2c_acpi_match[] = {
+ { "IIC1D17", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, zxi2c_acpi_match);
+
+static struct platform_driver zxi2c_driver = {
+ .probe = zxi2c_probe,
+ .driver = {
+ .name = ZXI2C_NAME,
+ .acpi_match_table = zxi2c_acpi_match,
+ .pm = &zxi2c_pm,
+ },
+};
+module_platform_driver(zxi2c_driver);
+
+MODULE_AUTHOR("HansHu@zhaoxin.com");
+MODULE_DESCRIPTION("Shanghai Zhaoxin IIC driver");
+MODULE_LICENSE("GPL");
--
2.34.1