On 15.12.2024 9:59 AM, Mukesh Kumar Savaliya wrote:
> Hi Konrad,
>
> On 12/13/2024 6:35 PM, Konrad Dybcio wrote:
>> On 29.11.2024 3:43 PM, Mukesh Kumar Savaliya wrote:
>>> Add support to share I2C controller in multiprocessor system in a mutually
>>> exclusive way. Use "qcom,shared-se" flag in a particular i2c instance node
>>> if the usecase requires i2c controller to be shared.
>>>
>>> Sharing of I2C SE(Serial engine) is possible only for GSI mode as client
>>> from each processor can queue transfers over its own GPII Channel. For
>>> non GSI mode, we should force disable this feature even if set by user
>>> from DT by mistake.
>>>
>>> I2C driver just need to mark first_msg and last_msg flag to help indicate
>>> GPI driver to take lock and unlock TRE there by protecting from concurrent
>>> access from other EE or Subsystem.
>>>
>>> gpi_create_i2c_tre() function at gpi.c will take care of adding Lock and
>>> Unlock TRE for the respective transfer operations.
>>>
>>> Since the GPIOs are also shared between two SS, do not unconfigure them
>>> during runtime suspend. This will allow other SS to continue to transfer
>>> the data without any disturbance over the IO lines.
>>>
>>> For example, Assume an I2C EEPROM device connected with an I2C controller.
>>> Each client from ADSP and APPS processor can perform i2c transactions
>>> without any disturbance from each other.
>>>
>>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@xxxxxxxxxxx>
>>> ---
>>> drivers/i2c/busses/i2c-qcom-geni.c | 22 +++++++++++++++++++---
>>> 1 file changed, 19 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>>> index 7a22e1f46e60..ccf9933e2dad 100644
>>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>>> @@ -1,5 +1,6 @@
>>> // SPDX-License-Identifier: GPL-2.0
>>> // Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
>>> +// Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
>>> #include <linux/acpi.h>
>>> #include <linux/clk.h>
>>> @@ -617,6 +618,7 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
>>> peripheral.clk_div = itr->clk_div;
>>> peripheral.set_config = 1;
>>> peripheral.multi_msg = false;
>>> + peripheral.shared_se = gi2c->se.shared_geni_se;
>>> for (i = 0; i < num; i++) {
>>> gi2c->cur = &msgs[i];
>>> @@ -627,6 +629,8 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
>>> if (i < num - 1)
>>> peripheral.stretch = 1;
>>> + peripheral.first_msg = (i == 0);
>>> + peripheral.last_msg = (i == num - 1);
>>> peripheral.addr = msgs[i].addr;
>>> ret = geni_i2c_gpi(gi2c, &msgs[i], &config,
>>> @@ -815,6 +819,11 @@ static int geni_i2c_probe(struct platform_device *pdev)
>>> gi2c->clk_freq_out = KHZ(100);
>>> }
>>> + if (of_property_read_bool(pdev->dev.of_node, "qcom,shared-se")) {
>>> + gi2c->se.shared_geni_se = true;
>>> + dev_dbg(&pdev->dev, "I2C is shared between subsystems\n");
>>> + }
>>> +
>>> if (has_acpi_companion(dev))
>>> ACPI_COMPANION_SET(&gi2c->adap.dev, ACPI_COMPANION(dev));
>>> @@ -887,8 +896,10 @@ static int geni_i2c_probe(struct platform_device *pdev)
>>> else
>>> fifo_disable = readl_relaxed(gi2c->se.base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
>>> - if (fifo_disable) {
>>> - /* FIFO is disabled, so we can only use GPI DMA */
>>> + if (fifo_disable || gi2c->se.shared_geni_se) {
>>> + /* FIFO is disabled, so we can only use GPI DMA.
>>> + * SE can be shared in GSI mode between subsystems, each SS owns a GPII.
>>> + **/
>>
>> I don't think this change makes things clearer, I would drop it
> Shall i revert back to previous change ? What's your suggestion ?
Yes, drop changing this comment.
Konrad
