Re: [PATCH v2 4/6] phy: samsung: phy-exynos-pcie: rework driver to support Exynos5433 PCIe PHY

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hi Rob,

On 26.10.2020 19:50, Rob Herring wrote:
> On Fri, Oct 23, 2020 at 2:58 AM Marek Szyprowski
> <m.szyprowski@samsung.com> wrote:
>> From: Jaehoon Chung <jh80.chung@samsung.com>
>>
>> Exynos5440 SoC support has been dropped since commit 8c83315da1cf ("ARM:
>> dts: exynos: Remove Exynos5440"). Rework this driver to support PCIe PHY
>> variant found in the Exynos5433 SoCs.
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> [mszyprow: reworked the driver to support only Exynos5433 variant, rebased
>>             onto current kernel code, rewrote commit message]
>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
>> Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
>> ---
>>   drivers/phy/samsung/phy-exynos-pcie.c | 304 ++++++++++----------------
>>   1 file changed, 112 insertions(+), 192 deletions(-)
>>
>> diff --git a/drivers/phy/samsung/phy-exynos-pcie.c b/drivers/phy/samsung/phy-exynos-pcie.c
>> index 7e28b1aea0d1..d91de323dd0e 100644
>> --- a/drivers/phy/samsung/phy-exynos-pcie.c
>> +++ b/drivers/phy/samsung/phy-exynos-pcie.c
>> @@ -4,70 +4,41 @@
>>    *
>>    * Phy provider for PCIe controller on Exynos SoC series
>>    *
>> - * Copyright (C) 2017 Samsung Electronics Co., Ltd.
>> + * Copyright (C) 2017-2020 Samsung Electronics Co., Ltd.
>>    * Jaehoon Chung <jh80.chung@samsung.com>
>>    */
>>
>> -#include <linux/delay.h>
>>   #include <linux/io.h>
>> -#include <linux/iopoll.h>
>> -#include <linux/init.h>
>>   #include <linux/mfd/syscon.h>
>> -#include <linux/of.h>
>> -#include <linux/of_address.h>
>>   #include <linux/of_platform.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/phy/phy.h>
>>   #include <linux/regmap.h>
>>
>> -/* PCIe Purple registers */
>> -#define PCIE_PHY_GLOBAL_RESET          0x000
>> -#define PCIE_PHY_COMMON_RESET          0x004
>> -#define PCIE_PHY_CMN_REG               0x008
>> -#define PCIE_PHY_MAC_RESET             0x00c
>> -#define PCIE_PHY_PLL_LOCKED            0x010
>> -#define PCIE_PHY_TRSVREG_RESET         0x020
>> -#define PCIE_PHY_TRSV_RESET            0x024
>> -
>> -/* PCIe PHY registers */
>> -#define PCIE_PHY_IMPEDANCE             0x004
>> -#define PCIE_PHY_PLL_DIV_0             0x008
>> -#define PCIE_PHY_PLL_BIAS              0x00c
>> -#define PCIE_PHY_DCC_FEEDBACK          0x014
>> -#define PCIE_PHY_PLL_DIV_1             0x05c
>> -#define PCIE_PHY_COMMON_POWER          0x064
>> -#define PCIE_PHY_COMMON_PD_CMN         BIT(3)
>> -#define PCIE_PHY_TRSV0_EMP_LVL         0x084
>> -#define PCIE_PHY_TRSV0_DRV_LVL         0x088
>> -#define PCIE_PHY_TRSV0_RXCDR           0x0ac
>> -#define PCIE_PHY_TRSV0_POWER           0x0c4
>> -#define PCIE_PHY_TRSV0_PD_TSV          BIT(7)
>> -#define PCIE_PHY_TRSV0_LVCC            0x0dc
>> -#define PCIE_PHY_TRSV1_EMP_LVL         0x144
>> -#define PCIE_PHY_TRSV1_RXCDR           0x16c
>> -#define PCIE_PHY_TRSV1_POWER           0x184
>> -#define PCIE_PHY_TRSV1_PD_TSV          BIT(7)
>> -#define PCIE_PHY_TRSV1_LVCC            0x19c
>> -#define PCIE_PHY_TRSV2_EMP_LVL         0x204
>> -#define PCIE_PHY_TRSV2_RXCDR           0x22c
>> -#define PCIE_PHY_TRSV2_POWER           0x244
>> -#define PCIE_PHY_TRSV2_PD_TSV          BIT(7)
>> -#define PCIE_PHY_TRSV2_LVCC            0x25c
>> -#define PCIE_PHY_TRSV3_EMP_LVL         0x2c4
>> -#define PCIE_PHY_TRSV3_RXCDR           0x2ec
>> -#define PCIE_PHY_TRSV3_POWER           0x304
>> -#define PCIE_PHY_TRSV3_PD_TSV          BIT(7)
>> -#define PCIE_PHY_TRSV3_LVCC            0x31c
>> -
>> -struct exynos_pcie_phy_data {
>> -       const struct phy_ops    *ops;
>> -};
>> +#define PCIE_PHY_OFFSET(x)             ((x) * 0x4)
>> +
>> +/* Sysreg FSYS register offsets and bits for Exynos5433 */
>> +#define PCIE_EXYNOS5433_PHY_MAC_RESET          0x0208
>> +#define PCIE_MAC_RESET_MASK                    0xFF
>> +#define PCIE_MAC_RESET                         BIT(4)
>> +#define PCIE_EXYNOS5433_PHY_L1SUB_CM_CON       0x1010
>> +#define PCIE_REFCLK_GATING_EN                  BIT(0)
>> +#define PCIE_EXYNOS5433_PHY_COMMON_RESET       0x1020
>> +#define PCIE_PHY_RESET                         BIT(0)
>> +#define PCIE_EXYNOS5433_PHY_GLOBAL_RESET       0x1040
>> +#define PCIE_GLOBAL_RESET                      BIT(0)
> Resets, why is this block not a reset provider?

Because most of those registers need to be configured together with the 
rest of the PHY registers. IMHO there is no simple "do the reset" logic 
there. There is also PHY reference clock configuration there. This phy 
driver is already Exynos5433 specific and I see no point in extracting 
separate reset driver from it. Other Exynos PHY drivers also access PMU 
and SYSREG via the respective regmaps and don't use any kind of reset 
drivers.

>> +#define PCIE_REFCLK                            BIT(1)
>> +#define PCIE_REFCLK_MASK                       0x16
>> +#define PCIE_APP_REQ_EXIT_L1_MODE              BIT(5)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland