Re: [PATCH v6 1/4] phy: cadence: Add Cadence D-PHY Rx driver

On 23-12-21, 00:15, Pratyush Yadav wrote:

On 20/12/21 04:31PM, Paul Kocialkowski wrote:

quoted

Hi Pratyush,

On Tue 14 Dec 21, 23:37, Pratyush Yadav wrote:

quoted

The Cadence D-PHY can be configured in Tx (DSI) mode or Rx (CSI) mode.
Both modes have a different programming sequence and share little among
them. In addition, a PHY configured in Tx mode cannot be used in Rx mode
and vice versa. For this reason, create a separate driver for the Rx
mode to make it easier to read and maintain.

Signed-off-by: Pratyush Yadav <redacted>

---

Changes in v6:
- Move to a separate driver.

Changes in v5:
- Use the new cdns_dphy_info to specify PHY ops.
- Re-order include in alphabetical order.
- Make bands const.
- Drop num_bands.
- Make i, lanes unsigned.
- Drop the maximum check in cdns_dphy_rx_get_band_ctrl(). Let the loop
  complete and return -EOPNOTSUPP when we reach the end.
- Drop the "rate < bands[i].min_rate" check since the bands are in
  ascending order.
- Move data_lane_ctrl to start of function and make it static const.

Changes in v4:
- Drop the submode parts. Use a different compatible for the Rx ops.
- Make bands and num_bands static.

Changes in v3:
- Use a table to select the band.
- Use a table to poll the data lane ready bits.
- Multiply the DPHY HS clock rate by 2 to get the bit rate since the
  clock is DDR.

 drivers/phy/cadence/Kconfig        |   8 +
 drivers/phy/cadence/Makefile       |   1 +
 drivers/phy/cadence/cdns-dphy-rx.c | 250 +++++++++++++++++++++++++++++
 3 files changed, 259 insertions(+)
 create mode 100644 drivers/phy/cadence/cdns-dphy-rx.c

diff --git a/drivers/phy/cadence/Kconfig b/drivers/phy/cadence/Kconfig
index a62910ff5591..1adde2d99ae7 100644
--- a/drivers/phy/cadence/Kconfig
+++ b/drivers/phy/cadence/Kconfig

@@ -22,6 +22,14 @@ config PHY_CADENCE_DPHY
 	  system. If M is selected, the module will be called
 	  cdns-dphy.
 
+config PHY_CADENCE_DPHY_RX
+	tristate "Cadence D-PHY Rx Support"
+	depends on HAS_IOMEM && OF
+	select GENERIC_PHY
+	select GENERIC_PHY_MIPI_DPHY
+	help
+	  Support for Cadence D-PHY in Rx configuration.
+
 config PHY_CADENCE_SIERRA
 	tristate "Cadence Sierra PHY Driver"
 	depends on OF && HAS_IOMEM && RESET_CONTROLLER

diff --git a/drivers/phy/cadence/Makefile b/drivers/phy/cadence/Makefile
index 26e16bd34efe..e17f035ddece 100644
--- a/drivers/phy/cadence/Makefile
+++ b/drivers/phy/cadence/Makefile

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_PHY_CADENCE_TORRENT)	+= phy-cadence-torrent.o
 obj-$(CONFIG_PHY_CADENCE_DPHY)	+= cdns-dphy.o
+obj-$(CONFIG_PHY_CADENCE_DPHY_RX)	+= cdns-dphy-rx.o
 obj-$(CONFIG_PHY_CADENCE_SIERRA)	+= phy-cadence-sierra.o
 obj-$(CONFIG_PHY_CADENCE_SALVO)	+= phy-cadence-salvo.o

diff --git a/drivers/phy/cadence/cdns-dphy-rx.c b/drivers/phy/cadence/cdns-dphy-rx.c
new file mode 100644
index 000000000000..fb75e645e662
--- /dev/null
+++ b/drivers/phy/cadence/cdns-dphy-rx.c

@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/phy/phy.h>
+#include <linux/phy/phy-mipi-dphy.h>
+#include <linux/platform_device.h>
+
+#define DPHY_PMA_CMN(reg)		(reg)
+#define DPHY_PCS(reg)			(0xb00 + (reg))
+#define DPHY_ISO(reg)			(0xc00 + (reg))
+
+#define DPHY_CMN_SSM			DPHY_PMA_CMN(0x20)
+#define DPHY_CMN_RX_MODE_EN		BIT(10)
+#define DPHY_CMN_RX_BANDGAP_TIMER_MASK	GENMASK(8, 1)
+#define DPHY_CMN_SSM_EN			BIT(0)
+
+#define DPHY_CMN_RX_BANDGAP_TIMER	0x14
+
+#define DPHY_BAND_CFG			DPHY_PCS(0x0)
+#define DPHY_BAND_CFG_RIGHT_BAND	GENMASK(9, 5)
+#define DPHY_BAND_CFG_LEFT_BAND		GENMASK(4, 0)
+
+#define DPHY_POWER_ISLAND_EN_DATA	DPHY_PCS(0x8)
+#define DPHY_POWER_ISLAND_EN_DATA_VAL	0xaaaaaaaa
+
+#define DPHY_POWER_ISLAND_EN_CLK	DPHY_PCS(0xc)
+#define DPHY_POWER_ISLAND_EN_CLK_VAL	0xaa
+
+#define DPHY_ISO_CL_CTRL_L		DPHY_ISO(0x10)
+#define DPHY_ISO_DL_CTRL_L0		DPHY_ISO(0x14)
+#define DPHY_ISO_DL_CTRL_L1		DPHY_ISO(0x20)
+#define DPHY_ISO_DL_CTRL_L2		DPHY_ISO(0x30)
+#define DPHY_ISO_DL_CTRL_L3		DPHY_ISO(0x3c)
+
+#define DPHY_ISO_LANE_READY_BIT		0
+#define DPHY_ISO_LANE_READY_TIMEOUT_MS	100UL
+
+#define DPHY_LANES_MIN			1
+#define DPHY_LANES_MAX			4
+
+struct cdns_dphy_rx {
+	void __iomem *regs;
+	struct device *dev;
+	struct phy *phy;
+};
+
+struct cdns_dphy_rx_band {
+	/* Rates are in Mbps. */
+	unsigned int min_rate;
+	unsigned int max_rate;
+};
+
+/* Order of bands is important since the index is the band number. */
+static const struct cdns_dphy_rx_band bands[] = {
+	{80, 100}, {100, 120}, {120, 160}, {160, 200}, {200, 240},
+	{240, 280}, {280, 320}, {320, 360}, {360, 400}, {400, 480},
+	{480, 560}, {560, 640}, {640, 720}, {720, 800}, {800, 880},
+	{880, 1040}, {1040, 1200}, {1200, 1350}, {1350, 1500}, {1500, 1750},
+	{1750, 2000}, {2000, 2250}, {2250, 2500}

Cosmetic suggestion: add whitespaces after { and before }.

I think it would just add noise. I would like to keep it compact.

No, it makes it look lot more neater and is usually the convention
followed in kernel

-- 
~Vinod