The RTL9300 I2C controller can support multiplexing by choosing the SDA
pin to be used dynamically. Add mutliplexing support to the rtl9300
driver.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
drivers/i2c/busses/i2c-rtl9300.c | 168 ++++++++++++++++++++++++++++++-
1 file changed, 167 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
index f16e9b6343bf..a934a2526c92 100644
--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
#include <linux/mod_devicetable.h>
#include <linux/mfd/syscon.h>
#include <linux/mutex.h>
@@ -44,6 +45,14 @@ struct rtl9300_i2c {
#define RTL9300_I2C_STD_FREQ 0
#define RTL9300_I2C_FAST_FREQ 1
+struct rtl9300_i2c_chan {
+ int parent;
+ const unsigned int *chans;
+ int n_chan;
+};
+
+#define RTL9300_I2C_MUX_NCHAN 8
+
DEFINE_MUTEX(i2c_lock);
static int rtl9300_i2c_reg_addr_set(struct rtl9300_i2c *i2c, u32 reg, u16 len)
@@ -370,7 +379,164 @@ static struct platform_driver rtl9300_i2c_driver = {
},
};
-module_platform_driver(rtl9300_i2c_driver);
+static int rtl9300_i2c_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct i2c_adapter *adap = muxc->parent;
+ struct rtl9300_i2c *i2c = i2c_get_adapdata(adap);
+ int ret;
+
+ ret = rtl9300_i2c_config_io(i2c, chan);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int rtl9300_i2c_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct i2c_adapter *adap = muxc->parent;
+ struct rtl9300_i2c *i2c = i2c_get_adapdata(adap);
+ int ret;
+
+ ret = rtl9300_i2c_config_io(i2c, i2c->sda_pin);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int rtl9300_i2c_mux_probe_fw(struct rtl9300_i2c_chan *mux, struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct fwnode_handle *fwnode = dev_fwnode(dev);
+ struct device_node *np = dev->of_node;
+ struct device_node *adap_np;
+ struct i2c_adapter *adap = NULL;
+ struct fwnode_handle *child;
+ unsigned int *chans;
+ int i = 0;
+
+ if (!is_of_node(fwnode))
+ return -EOPNOTSUPP;
+
+ if (!np)
+ return -ENODEV;
+
+ adap_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!adap_np) {
+ dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+ return -ENODEV;
+ }
+ adap = of_find_i2c_adapter_by_node(adap_np);
+ of_node_put(adap_np);
+
+ if (!adap)
+ return -EPROBE_DEFER;
+
+ mux->parent = i2c_adapter_id(adap);
+ put_device(&adap->dev);
+
+ mux->n_chan = device_get_child_node_count(dev);
+ if (mux->n_chan >= RTL9300_I2C_MUX_NCHAN)
+ return -EINVAL;
+
+ chans = devm_kcalloc(dev, mux->n_chan, sizeof(*mux->chans), GFP_KERNEL);
+ if (!chans)
+ return -ENOMEM;
+
+ device_for_each_child_node(dev, child) {
+ fwnode_property_read_u32(child, "reg", chans + i);
+ i++;
+ }
+ mux->chans = chans;
+
+ return 0;
+}
+
+static int rtl9300_i2c_mux_probe(struct platform_device *pdev)
+{
+ struct i2c_mux_core *muxc;
+ struct i2c_adapter *adap;
+ struct rtl9300_i2c_chan *mux;
+ int ret, i;
+
+ mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux)
+ return -ENOMEM;
+
+ ret = rtl9300_i2c_mux_probe_fw(mux, pdev);
+ if (ret)
+ return ret;
+
+ adap = i2c_get_adapter(mux->parent);
+ if (!adap)
+ return -EPROBE_DEFER;
+
+ muxc = i2c_mux_alloc(adap, &pdev->dev, mux->n_chan, 0, 0,
+ rtl9300_i2c_select_chan, rtl9300_i2c_deselect_mux);
+ if (!muxc) {
+ ret = -ENOMEM;
+ goto err_alloc;
+ }
+ muxc->priv = mux;
+
+ platform_set_drvdata(pdev, muxc);
+
+ for (i = 0; i < mux->n_chan; i++) {
+ ret = i2c_mux_add_adapter(muxc, 0, mux->chans[i]);
+ if (ret)
+ goto err_del_adapters;
+ }
+
+ return 0;
+
+err_del_adapters:
+ i2c_mux_del_adapters(muxc);
+err_alloc:
+ i2c_put_adapter(adap);
+
+ return ret;
+}
+
+static void rtl9300_i2c_mux_remove(struct platform_device *pdev)
+{
+ struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+ i2c_mux_del_adapters(muxc);
+ i2c_put_adapter(muxc->parent);
+}
+
+static const struct of_device_id i2c_rtl9300_mux_dt_ids[] = {
+ { .compatible = "realtek,rtl9300-i2c-mux" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, i2c_rtl9300_mux_dt_ids);
+
+static struct platform_driver rtl9300_i2c_mux_driver = {
+ .probe = rtl9300_i2c_mux_probe,
+ .remove = rtl9300_i2c_mux_remove,
+ .driver = {
+ .name = "i2c-mux-rtl9300",
+ .of_match_table = i2c_rtl9300_mux_dt_ids,
+ },
+};
+
+static struct platform_driver * const drivers[] = {
+ &rtl9300_i2c_driver,
+ &rtl9300_i2c_mux_driver,
+};
+
+static int __init rtl9300_i2c_init(void)
+{
+ return platform_register_drivers(drivers, ARRAY_SIZE(drivers));
+}
+module_init(rtl9300_i2c_init);
+
+static void __exit rtl9300_i2c_exit(void)
+{
+ platform_unregister_drivers(drivers, ARRAY_SIZE(drivers));
+}
+module_exit(rtl9300_i2c_exit);
MODULE_DESCRIPTION("RTL9300 I2C controller driver");
MODULE_LICENSE("GPL");
--
2.46.1Hi Chris,
...
> -module_platform_driver(rtl9300_i2c_driver);
> +static int rtl9300_i2c_select_chan(struct i2c_mux_core *muxc, u32 chan)
> +{
> + struct i2c_adapter *adap = muxc->parent;
> + struct rtl9300_i2c *i2c = i2c_get_adapdata(adap);
> + int ret;
> +
> + ret = rtl9300_i2c_config_io(i2c, chan);
> + if (ret)
> + return ret;
> +
> + return 0;
return "rtl9300_i2c_config_io()"?
> +}
...
> +static int rtl9300_i2c_mux_probe_fw(struct rtl9300_i2c_chan *mux, struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct fwnode_handle *fwnode = dev_fwnode(dev);
> + struct device_node *np = dev->of_node;
> + struct device_node *adap_np;
> + struct i2c_adapter *adap = NULL;
> + struct fwnode_handle *child;
> + unsigned int *chans;
> + int i = 0;
> +
> + if (!is_of_node(fwnode))
> + return -EOPNOTSUPP;
> +
> + if (!np)
> + return -ENODEV;
> +
> + adap_np = of_parse_phandle(np, "i2c-parent", 0);
> + if (!adap_np) {
> + dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
> + return -ENODEV;
return dev_err_probe(...)?
> + }
> + adap = of_find_i2c_adapter_by_node(adap_np);
> + of_node_put(adap_np);
...
> +static int __init rtl9300_i2c_init(void)
> +{
> + return platform_register_drivers(drivers, ARRAY_SIZE(drivers));
> +}
> +module_init(rtl9300_i2c_init);
> +
> +static void __exit rtl9300_i2c_exit(void)
> +{
> + platform_unregister_drivers(drivers, ARRAY_SIZE(drivers));
> +}
> +module_exit(rtl9300_i2c_exit);
You could use module_platform_driver()
Thanks,
Andi
>
> MODULE_DESCRIPTION("RTL9300 I2C controller driver");
> MODULE_LICENSE("GPL");
> --
> 2.46.1
>
Hi Andi, Rob,
On 19/09/24 08:36, Andi Shyti wrote:
> Hi Chris,
>
> ...
>
>> -module_platform_driver(rtl9300_i2c_driver);
>> +static int rtl9300_i2c_select_chan(struct i2c_mux_core *muxc, u32 chan)
>> +{
>> + struct i2c_adapter *adap = muxc->parent;
>> + struct rtl9300_i2c *i2c = i2c_get_adapdata(adap);
>> + int ret;
>> +
>> + ret = rtl9300_i2c_config_io(i2c, chan);
>> + if (ret)
>> + return ret;
>> +
>> + return 0;
> return "rtl9300_i2c_config_io()"?
Ack.
>> +}
> ...
>
>> +static int rtl9300_i2c_mux_probe_fw(struct rtl9300_i2c_chan *mux, struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct fwnode_handle *fwnode = dev_fwnode(dev);
>> + struct device_node *np = dev->of_node;
>> + struct device_node *adap_np;
>> + struct i2c_adapter *adap = NULL;
>> + struct fwnode_handle *child;
>> + unsigned int *chans;
>> + int i = 0;
>> +
>> + if (!is_of_node(fwnode))
>> + return -EOPNOTSUPP;
>> +
>> + if (!np)
>> + return -ENODEV;
>> +
>> + adap_np = of_parse_phandle(np, "i2c-parent", 0);
>> + if (!adap_np) {
>> + dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
>> + return -ENODEV;
> return dev_err_probe(...)?
Ack.
>> + }
>> + adap = of_find_i2c_adapter_by_node(adap_np);
>> + of_node_put(adap_np);
> ...
>
>> +static int __init rtl9300_i2c_init(void)
>> +{
>> + return platform_register_drivers(drivers, ARRAY_SIZE(drivers));
>> +}
>> +module_init(rtl9300_i2c_init);
>> +
>> +static void __exit rtl9300_i2c_exit(void)
>> +{
>> + platform_unregister_drivers(drivers, ARRAY_SIZE(drivers));
>> +}
>> +module_exit(rtl9300_i2c_exit);
> You could use module_platform_driver()
Can I though? I want to support both the simple I2C controller and the
MUX mode with the same driver. Which is why I've ended up with two
drivers to register.
On the binding patch, Rob made the suggestion that I just make the
i2c-mux part of the parent. I did consider that but quickly got tied in
knots because I couldn't figure out how to have a device that is both an
adapter and a mux. The main problem was that any child nodes of an i2c
adapter in the device tree are presumed to be I2C devices and get probed
automatically by of_i2c_register_devices(). Equally I can't register a
mux without having an adapter that the mux operates over.
>
> Thanks,
> Andi
>
>>
>> MODULE_DESCRIPTION("RTL9300 I2C controller driver");
>> MODULE_LICENSE("GPL");
>> --
>> 2.46.1
>>
On 19/09/24 09:44, Chris Packham wrote:
> Hi Andi, Rob,
>
> On 19/09/24 08:36, Andi Shyti wrote:
>> Hi Chris,
>>
>> ...
>>
>>> -module_platform_driver(rtl9300_i2c_driver);
>>> +static int rtl9300_i2c_select_chan(struct i2c_mux_core *muxc, u32
>>> chan)
>>> +{
>>> + struct i2c_adapter *adap = muxc->parent;
>>> + struct rtl9300_i2c *i2c = i2c_get_adapdata(adap);
>>> + int ret;
>>> +
>>> + ret = rtl9300_i2c_config_io(i2c, chan);
>>> + if (ret)
>>> + return ret;
>>> +
>>> + return 0;
>> return "rtl9300_i2c_config_io()"?
>
> Ack.
>
>>> +}
>> ...
>>
>>> +static int rtl9300_i2c_mux_probe_fw(struct rtl9300_i2c_chan *mux,
>>> struct platform_device *pdev)
>>> +{
>>> + struct device *dev = &pdev->dev;
>>> + struct fwnode_handle *fwnode = dev_fwnode(dev);
>>> + struct device_node *np = dev->of_node;
>>> + struct device_node *adap_np;
>>> + struct i2c_adapter *adap = NULL;
>>> + struct fwnode_handle *child;
>>> + unsigned int *chans;
>>> + int i = 0;
>>> +
>>> + if (!is_of_node(fwnode))
>>> + return -EOPNOTSUPP;
>>> +
>>> + if (!np)
>>> + return -ENODEV;
>>> +
>>> + adap_np = of_parse_phandle(np, "i2c-parent", 0);
>>> + if (!adap_np) {
>>> + dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
>>> + return -ENODEV;
>> return dev_err_probe(...)?
>
> Ack.
>
>>> + }
>>> + adap = of_find_i2c_adapter_by_node(adap_np);
>>> + of_node_put(adap_np);
>> ...
>>
>>> +static int __init rtl9300_i2c_init(void)
>>> +{
>>> + return platform_register_drivers(drivers, ARRAY_SIZE(drivers));
>>> +}
>>> +module_init(rtl9300_i2c_init);
>>> +
>>> +static void __exit rtl9300_i2c_exit(void)
>>> +{
>>> + platform_unregister_drivers(drivers, ARRAY_SIZE(drivers));
>>> +}
>>> +module_exit(rtl9300_i2c_exit);
>> You could use module_platform_driver()
>
> Can I though? I want to support both the simple I2C controller and the
> MUX mode with the same driver. Which is why I've ended up with two
> drivers to register.
>
> On the binding patch, Rob made the suggestion that I just make the
> i2c-mux part of the parent. I did consider that but quickly got tied
> in knots because I couldn't figure out how to have a device that is
> both an adapter and a mux. The main problem was that any child nodes
> of an i2c adapter in the device tree are presumed to be I2C devices
> and get probed automatically by of_i2c_register_devices(). Equally I
> can't register a mux without having an adapter that the mux operates
> over.
OK I think I've got something working that has a dt binding like
i2c@36c {
compatible = "realtek,rtl9300-i2c";
reg = <0x36c 0x14>;
status = "okay";
#address-cells = <0x01>;
#size-cells = <0x00>;
i2c@0 {
reg = <0x00>;
#address-cells = <1>;
#size-cells = <1>;
gpio@20 {
...
};
};
i2c@2 {
reg = <0x02>;
};
};
In the probe() I can iterate over the child nodes and create an adapter
for each. The code is a bit fiddly but I think it's a net win if I can
do away with the rtl9300-i2c-mux part. It also happily means that I
don't have an extra I2C bus that is the same as the first mux channel.
I'll try an tidy things up and get another iteration out before my weekend.
>
>>
>> Thanks,
>> Andi
>>
>>> MODULE_DESCRIPTION("RTL9300 I2C controller driver");
>>> MODULE_LICENSE("GPL");
>>> --
>>> 2.46.1
>>>
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