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Message-ID: <51e4f815-3745-65ec-55d1-1a0d9569ea70@amd.com>
Date: Thu, 25 Mar 2021 19:54:17 +0530
From: "Goswami, Sanket" <Sanket.Goswami@....com>
To: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
Shyam Sundar S K <Shyam-sundar.S-k@....com>,
Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
mika.westerberg@...ux.intel.com
Subject: Re: [PATCH v2] i2c: designware: Add driver support for AMD NAVI GPU
Hi Jarkko,
On 23-Mar-21 19:40, Jarkko Nikula wrote:
> [CAUTION: External Email]
>
> Hi
>
> On 3/22/21 6:59 PM, Sanket Goswami wrote:
>> The Latest AMD NAVI GPU card has an integrated Type-C controller and
>> Designware I2C with PCI Interface. The Type-C controller can be
>> accessed over I2C. The client driver is part of the USB Type-C UCSI
>> driver.
>>
>> Also, there exists a couple of notable IP limitations that are dealt as
>> workarounds:
>> - I2C transaction work on a polling mode as IP does not generate
>> interrupt.
>> - I2C read command sent twice to address the IP issues.
>>
>> Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
>> Co-developed-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
>> Signed-off-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
>> Signed-off-by: Sanket Goswami <Sanket.Goswami@....com>
>> ---
>> Changes in v2:
>> - Utilized existing functionality of i2c_dw_xfer_init to configure I2C
>> bus.
>> - Removed i2c_dw_populate_client and rewrrient navi_amd_register_client
>> to deduplicate from existing drivers.
>> - Addressed review comments from Andy.
>>
>> drivers/i2c/busses/i2c-designware-common.c | 3 +
>> drivers/i2c/busses/i2c-designware-core.h | 3 +
>> drivers/i2c/busses/i2c-designware-master.c | 136 +++++++++++++++++++++
>> drivers/i2c/busses/i2c-designware-pcidrv.c | 57 +++++++++
>> 4 files changed, 199 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
>> index 3c19aada4b30..50883a70b482 100644
>> --- a/drivers/i2c/busses/i2c-designware-common.c
>> +++ b/drivers/i2c/busses/i2c-designware-common.c
>> @@ -150,6 +150,9 @@ int i2c_dw_init_regmap(struct dw_i2c_dev *dev)
>> reg = readl(dev->base + DW_IC_COMP_TYPE);
>> i2c_dw_release_lock(dev);
>>
>> + if (dev->flags & AMD_NON_INTR_MODE)
>> + map_cfg.max_register = AMD_UCSI_INTR_REG;
>> +
>> if (reg == swab32(DW_IC_COMP_TYPE_VALUE)) {
>> map_cfg.reg_read = dw_reg_read_swab;
>> map_cfg.reg_write = dw_reg_write_swab;
>> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
>> index 5392b82f68a4..f29923c452ac 100644
>> --- a/drivers/i2c/busses/i2c-designware-core.h
>> +++ b/drivers/i2c/busses/i2c-designware-core.h
>> @@ -293,9 +293,12 @@ struct dw_i2c_dev {
>> #define ACCESS_INTR_MASK BIT(0)
>> #define ACCESS_NO_IRQ_SUSPEND BIT(1)
>>
>> +#define AMD_NON_INTR_MODE BIT(2)
>> #define MODEL_MSCC_OCELOT BIT(8)
>> #define MODEL_BAIKAL_BT1 BIT(9)
>> #define MODEL_MASK GENMASK(11, 8)
>> +#define AMD_UCSI_INTR_EN 0xd
>> +#define AMD_UCSI_INTR_REG 0x474
>>
>> int i2c_dw_init_regmap(struct dw_i2c_dev *dev);
>> u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset);
>> diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
>> index dd27b9dbe931..a76e1f992850 100644
>> --- a/drivers/i2c/busses/i2c-designware-master.c
>> +++ b/drivers/i2c/busses/i2c-designware-master.c
>> @@ -23,6 +23,10 @@
>>
>> #include "i2c-designware-core.h"
>>
>> +#define AMD_TIMEOUT_MIN_MSEC 10000
>> +#define AMD_TIMEOUT_MAX_MSEC 11000
>> +#define AMD_MASTERCFG_MASK GENMASK(15, 0)
>> +
>> static void i2c_dw_configure_fifo_master(struct dw_i2c_dev *dev)
>> {
>> /* Configure Tx/Rx FIFO threshold levels */
>> @@ -208,6 +212,13 @@ static int i2c_dw_init_master(struct dw_i2c_dev *dev)
>> if (dev->sda_hold_time)
>> regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
>>
>> + /*
>> + * In order to enable the interrupt for UCSI i.e. AMD NAVI GPU card,
>> + * it is mandatory to set the right value in specific register
>> + * (offset:0x474) as per the hardware IP specification.
>> + */
>> + if (dev->flags & AMD_NON_INTR_MODE)
>> + regmap_write(dev->map, AMD_UCSI_INTR_REG, AMD_UCSI_INTR_EN);
>
> This confuses me - this patch is about adding support for DesignWare IP
> that does not generate interrupts but here code is enabling an
> interrupt. I guess it's for UCSI but should above code then go to a
> driver handling that IP?
That's true, This patch is regarding DesignWare IP. However, interrupt enablement for
UCSI has to be performed from the I2C master driver as AMD_UCSI_INTR_REG is part of this
DesignWare IP specification. Hence, we feel this should not be part of the UCSI driver.
Please suggest if you have any alternate thoughts.
>
>> +static int i2c_dw_check_stopbit(struct dw_i2c_dev *i2cd)
> ...
>> +static int i2c_dw_status(struct dw_i2c_dev *i2cd)
> ...
>> +static int amd_i2c_dw_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num_msgs)
> ...
>> +{
>> + struct dw_i2c_dev *i2cd = i2c_get_adapdata(adap);
>
> For uniformity I'd use struct dw_i2c_dev *dev name instead of *i2cd
> since that what driver uses currently in other places.
Got your point, it will be addressed in v3.
>
>> @@ -461,6 +587,13 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>> dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
>>
>> pm_runtime_get_sync(dev->dev);
>> + /*
>> + * Initiate I2C message transfer when AMD NAVI GPU card is enabled,
>> + * As it is polling based transfer mechanism, which does not support
>> + * interrupt based functionalities of existing DesignWare driver.
>> + */
>> + if (dev->flags & AMD_NON_INTR_MODE)
>> + return amd_i2c_dw_master_xfer(adap, msgs, num);
>>
> Does runtime PM go out of sync here?
Thanks for pointing out this, It will be also addressed in v3.
>
> Jarkko
Thanks,
Sanket
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