Re: [PATCH v2 8/9] phy: Add Cadence D-PHY support

[Kishon Vijay Abraham I <kishon@ti.com>]

Hi,

On 12/11/18 3:21 PM, Kishon Vijay Abraham I wrote:
> Hi Maxime,
> 
> On 06/11/18 8:24 PM, Maxime Ripard wrote:
>> Cadence has designed a D-PHY that can be used by the, currently in tree,
>> DSI bridge (DRM), CSI Transceiver and CSI Receiver (v4l2) drivers.
>>
>> Only the DSI driver has an ad-hoc driver for that phy at the moment, while
>> the v4l2 drivers are completely missing any phy support. In order to make
>> that phy support available to all these drivers, without having to
>> duplicate that code three times, let's create a generic phy framework
>> driver.
>>
>> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
>> ---
>>   Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt |  21 +-
>>   Documentation/devicetree/bindings/phy/cdns,dphy.txt           |  20 +-
>>   drivers/phy/cadence/Kconfig                                   |  13 +-
>>   drivers/phy/cadence/Makefile                                  |   1 +-
>>   drivers/phy/cadence/cdns-dphy.c                               | 459 +++++++-
>>   5 files changed, 492 insertions(+), 22 deletions(-)
>>   create mode 100644 Documentation/devicetree/bindings/phy/cdns,dphy.txt
>>   create mode 100644 drivers/phy/cadence/cdns-dphy.c
>>
>> diff --git a/Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt b/Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt
>> index f5725bb6c61c..525a4bfd8634 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt
>> +++ b/Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt
>> @@ -31,28 +31,7 @@ Required subnodes:
>>   - one subnode per DSI device connected on the DSI bus. Each DSI device should
>>     contain a reg property encoding its virtual channel.
>>   
>> -Cadence DPHY
>> -============
>> -
>> -Cadence DPHY block.
>> -
>> -Required properties:
>> -- compatible: should be set to "cdns,dphy".
>> -- reg: physical base address and length of the DPHY registers.
>> -- clocks: DPHY reference clocks.
>> -- clock-names: must contain "psm" and "pll_ref".
>> -- #phy-cells: must be set to 0.
>> -
>> -
>>   Example:
>> -	dphy0: dphy@fd0e0000{
>> -		compatible = "cdns,dphy";
>> -		reg = <0x0 0xfd0e0000 0x0 0x1000>;
>> -		clocks = <&psm_clk>, <&pll_ref_clk>;
>> -		clock-names = "psm", "pll_ref";
>> -		#phy-cells = <0>;
>> -	};
>> -
>>   	dsi0: dsi@fd0c0000 {
>>   		compatible = "cdns,dsi";
>>   		reg = <0x0 0xfd0c0000 0x0 0x1000>;
>> diff --git a/Documentation/devicetree/bindings/phy/cdns,dphy.txt b/Documentation/devicetree/bindings/phy/cdns,dphy.txt
>> new file mode 100644
>> index 000000000000..1095bc4e72d9
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/phy/cdns,dphy.txt
>> @@ -0,0 +1,20 @@
>> +Cadence DPHY
>> +============
>> +
>> +Cadence DPHY block.
>> +
>> +Required properties:
>> +- compatible: should be set to "cdns,dphy".
>> +- reg: physical base address and length of the DPHY registers.
>> +- clocks: DPHY reference clocks.
>> +- clock-names: must contain "psm" and "pll_ref".
>> +- #phy-cells: must be set to 0.
>> +
>> +Example:
>> +	dphy0: dphy@fd0e0000{
>> +		compatible = "cdns,dphy";
>> +		reg = <0x0 0xfd0e0000 0x0 0x1000>;
>> +		clocks = <&psm_clk>, <&pll_ref_clk>;
>> +		clock-names = "psm", "pll_ref";
>> +		#phy-cells = <0>;
>> +	};
>> diff --git a/drivers/phy/cadence/Kconfig b/drivers/phy/cadence/Kconfig
>> index 57fff7de4031..240effa81046 100644
>> --- a/drivers/phy/cadence/Kconfig
>> +++ b/drivers/phy/cadence/Kconfig
>> @@ -1,6 +1,7 @@
>>   #
>> -# Phy driver for Cadence MHDP DisplayPort controller
>> +# Phy drivers for Cadence IPs
>>   #
>> +
>>   config PHY_CADENCE_DP
>>   	tristate "Cadence MHDP DisplayPort PHY driver"
>>   	depends on OF
>> @@ -8,3 +9,13 @@ config PHY_CADENCE_DP
>>   	select GENERIC_PHY
>>   	help
>>   	  Support for Cadence MHDP DisplayPort PHY.
>> +
>> +config PHY_CADENCE_DPHY
>> +	tristate "Cadence D-PHY Support"
>> +	depends on HAS_IOMEM && OF
>> +	select GENERIC_PHY
>> +	select GENERIC_PHY_MIPI_DPHY
>> +	help
>> +	  Choose this option if you have a Cadence D-PHY in your
>> +	  system. If M is selected, the module will be called
>> +	  cdns-csi.
>> diff --git a/drivers/phy/cadence/Makefile b/drivers/phy/cadence/Makefile
>> index e5b0a11cf28a..64cb9ea66ceb 100644
>> --- a/drivers/phy/cadence/Makefile
>> +++ b/drivers/phy/cadence/Makefile
>> @@ -1 +1,2 @@
>>   obj-$(CONFIG_PHY_CADENCE_DP)	+= phy-cadence-dp.o
>> +obj-$(CONFIG_PHY_CADENCE_DPHY)	+= cdns-dphy.o
>> diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
>> new file mode 100644
>> index 000000000000..a398b401e5d3
>> --- /dev/null
>> +++ b/drivers/phy/cadence/cdns-dphy.c
>> @@ -0,0 +1,459 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright: 2017-2018 Cadence Design Systems, Inc.
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset.h>
>> +
>> +#include <linux/phy/phy.h>
>> +#include <linux/phy/phy-mipi-dphy.h>
>> +
>> +#define REG_WAKEUP_TIME_NS		800
>> +#define DPHY_PLL_RATE_HZ		108000000
>> +
>> +/* DPHY registers */
>> +#define DPHY_PMA_CMN(reg)		(reg)
>> +#define DPHY_PMA_LCLK(reg)		(0x100 + (reg))
>> +#define DPHY_PMA_LDATA(lane, reg)	(0x200 + ((lane) * 0x100) + (reg))
>> +#define DPHY_PMA_RCLK(reg)		(0x600 + (reg))
>> +#define DPHY_PMA_RDATA(lane, reg)	(0x700 + ((lane) * 0x100) + (reg))
>> +#define DPHY_PCS(reg)			(0xb00 + (reg))
>> +
>> +#define DPHY_CMN_SSM			DPHY_PMA_CMN(0x20)
>> +#define DPHY_CMN_SSM_EN			BIT(0)
>> +#define DPHY_CMN_TX_MODE_EN		BIT(9)
>> +
>> +#define DPHY_CMN_PWM			DPHY_PMA_CMN(0x40)
>> +#define DPHY_CMN_PWM_DIV(x)		((x) << 20)
>> +#define DPHY_CMN_PWM_LOW(x)		((x) << 10)
>> +#define DPHY_CMN_PWM_HIGH(x)		(x)
>> +
>> +#define DPHY_CMN_FBDIV			DPHY_PMA_CMN(0x4c)
>> +#define DPHY_CMN_FBDIV_VAL(low, high)	(((high) << 11) | ((low) << 22))
>> +#define DPHY_CMN_FBDIV_FROM_REG		(BIT(10) | BIT(21))
>> +
>> +#define DPHY_CMN_OPIPDIV		DPHY_PMA_CMN(0x50)
>> +#define DPHY_CMN_IPDIV_FROM_REG		BIT(0)
>> +#define DPHY_CMN_IPDIV(x)		((x) << 1)
>> +#define DPHY_CMN_OPDIV_FROM_REG		BIT(6)
>> +#define DPHY_CMN_OPDIV(x)		((x) << 7)
>> +
>> +#define DPHY_PSM_CFG			DPHY_PCS(0x4)
>> +#define DPHY_PSM_CFG_FROM_REG		BIT(0)
>> +#define DPHY_PSM_CLK_DIV(x)		((x) << 1)
>> +
>> +#define DSI_HBP_FRAME_OVERHEAD		12
>> +#define DSI_HSA_FRAME_OVERHEAD		14
>> +#define DSI_HFP_FRAME_OVERHEAD		6
>> +#define DSI_HSS_VSS_VSE_FRAME_OVERHEAD	4
>> +#define DSI_BLANKING_FRAME_OVERHEAD	6
>> +#define DSI_NULL_FRAME_OVERHEAD		6
>> +#define DSI_EOT_PKT_SIZE		4
>> +
>> +struct cdns_dphy_cfg {
>> +	u8 pll_ipdiv;
>> +	u8 pll_opdiv;
>> +	u16 pll_fbdiv;
>> +	unsigned int nlanes;
>> +};
>> +
>> +enum cdns_dphy_clk_lane_cfg {
>> +	DPHY_CLK_CFG_LEFT_DRIVES_ALL = 0,
>> +	DPHY_CLK_CFG_LEFT_DRIVES_RIGHT = 1,
>> +	DPHY_CLK_CFG_LEFT_DRIVES_LEFT = 2,
>> +	DPHY_CLK_CFG_RIGHT_DRIVES_ALL = 3,
>> +};
>> +
>> +struct cdns_dphy;
>> +struct cdns_dphy_ops {
>> +	int (*probe)(struct cdns_dphy *dphy);
>> +	void (*remove)(struct cdns_dphy *dphy);
>> +	void (*set_psm_div)(struct cdns_dphy *dphy, u8 div);
>> +	void (*set_clk_lane_cfg)(struct cdns_dphy *dphy,
>> +				 enum cdns_dphy_clk_lane_cfg cfg);
>> +	void (*set_pll_cfg)(struct cdns_dphy *dphy,
>> +			    const struct cdns_dphy_cfg *cfg);
>> +	unsigned long (*get_wakeup_time_ns)(struct cdns_dphy *dphy);
>> +};
>> +
>> +struct cdns_dphy {
>> +	struct cdns_dphy_cfg cfg;
>> +	void __iomem *regs;
>> +	struct clk *psm_clk;
>> +	struct clk *pll_ref_clk;
>> +	const struct cdns_dphy_ops *ops;
>> +	struct phy *phy;
>> +};
>> +
>> +static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
>> +				     struct cdns_dphy_cfg *cfg,
>> +				     struct phy_configure_opts_mipi_dphy *opts,
>> +				     unsigned int *dsi_hfp_ext)
>> +{
>> +	u64 dlane_bps, dlane_bps_max, fbdiv, fbdiv_max, adj_dsi_htotal;
>> +	unsigned long pll_ref_hz = clk_get_rate(dphy->pll_ref_clk);
>> +
>> +	memset(cfg, 0, sizeof(*cfg));
>> +
>> +	if (pll_ref_hz < 9600000 || pll_ref_hz >= 150000000)
>> +		return -EINVAL;
>> +	else if (pll_ref_hz < 19200000)
>> +		cfg->pll_ipdiv = 1;
>> +	else if (pll_ref_hz < 38400000)
>> +		cfg->pll_ipdiv = 2;
>> +	else if (pll_ref_hz < 76800000)
>> +		cfg->pll_ipdiv = 4;
>> +	else
>> +		cfg->pll_ipdiv = 8;
>> +
>> +	dlane_bps = opts->hs_clk_rate;
>> +
>> +	if (dlane_bps > 2500000000UL || dlane_bps < 160000000UL)
>> +		return -EINVAL;
>> +	else if (dlane_bps >= 1250000000)
>> +		cfg->pll_opdiv = 1;
>> +	else if (dlane_bps >= 630000000)
>> +		cfg->pll_opdiv = 2;
>> +	else if (dlane_bps >= 320000000)
>> +		cfg->pll_opdiv = 4;
>> +	else if (dlane_bps >= 160000000)
>> +		cfg->pll_opdiv = 8;
>> +
>> +	/*
>> +	 * Allow a deviation of 0.2% on the per-lane data rate to try to
>> +	 * recover a potential mismatch between DPI and PPI clks.
>> +	 */
>> +	dlane_bps_max = dlane_bps + DIV_ROUND_DOWN_ULL(dlane_bps, 500);
>> +	fbdiv_max = DIV_ROUND_DOWN_ULL(dlane_bps_max * 2 *
>> +				       cfg->pll_opdiv * cfg->pll_ipdiv,
>> +				       pll_ref_hz);
>> +	fbdiv = DIV_ROUND_UP_ULL(dlane_bps * 2 * cfg->pll_opdiv *
>> +				 cfg->pll_ipdiv,
>> +				 pll_ref_hz);
>> +
>> +	/*
>> +	 * Iterate over all acceptable fbdiv and try to find an adjusted DSI
>> +	 * htotal length providing an exact match.
>> +	 *
>> +	 * Note that we could do something even trickier by relying on the fact
>> +	 * that a new line is not necessarily aligned on a lane boundary, so,
>> +	 * by making adj_dsi_htotal non aligned on a dsi_lanes we can improve a
>> +	 * bit the precision. With this, the step would be
>> +	 *
>> +	 *	pll_ref_hz / (2 * opdiv * ipdiv * nlanes)
>> +	 *
>> +	 * instead of
>> +	 *
>> +	 *	pll_ref_hz / (2 * opdiv * ipdiv)
>> +	 *
>> +	 * The drawback of this approach is that we would need to make sure the
>> +	 * number or lines is a multiple of the realignment periodicity which is
>> +	 * a function of the number of lanes and the original misalignment. For
>> +	 * example, for NLANES = 4 and HTOTAL % NLANES = 3, it takes 4 lines
>> +	 * to realign on a lane:
>> +	 * LINE 0: expected number of bytes, starts emitting first byte of
>> +	 *	   LINE 1 on LANE 3
>> +	 * LINE 1: expected number of bytes, starts emitting first 2 bytes of
>> +	 *	   LINE 2 on LANES 2 and 3
>> +	 * LINE 2: expected number of bytes, starts emitting first 3 bytes of
>> +	 *	   of LINE 3 on LANES 1, 2 and 3
>> +	 * LINE 3: one byte less, now things are realigned on LANE 0 for LINE 4
>> +	 *
>> +	 * I figured this extra complexity was not worth the benefit, but if
>> +	 * someone really has unfixable mismatch, that would be something to
>> +	 * investigate.
>> +	 */
>> +	for (; fbdiv <= fbdiv_max; fbdiv++) {
>> +		u32 rem;
>> +
>> +		/*
>> +		 * Do the division in 2 steps to avoid an overflow on the
>> +		 * divider.
>> +		 */
>> +		rem = do_div(adj_dsi_htotal, opts->hs_clk_rate);
>> +		if (rem)
>> +			continue;
>> +
>> +		rem = do_div(adj_dsi_htotal,
>> +			     cfg->pll_opdiv * cfg->pll_ipdiv * 2 * 8);
>> +		if (rem)
>> +			continue;
>> +
>> +		cfg->pll_fbdiv = fbdiv;
>> +		break;
>> +	}
>> +
>> +	/* No match, let's just reject the display mode. */
>> +	if (!cfg->pll_fbdiv)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int cdns_dphy_setup_psm(struct cdns_dphy *dphy)
>> +{
>> +	unsigned long psm_clk_hz = clk_get_rate(dphy->psm_clk);
>> +	unsigned long psm_div;
>> +
>> +	if (!psm_clk_hz || psm_clk_hz > 100000000)
>> +		return -EINVAL;
>> +
>> +	psm_div = DIV_ROUND_CLOSEST(psm_clk_hz, 1000000);
>> +	if (dphy->ops->set_psm_div)
>> +		dphy->ops->set_psm_div(dphy, psm_div);
>> +
>> +	return 0;
>> +}
>> +
>> +static void cdns_dphy_set_clk_lane_cfg(struct cdns_dphy *dphy,
>> +				       enum cdns_dphy_clk_lane_cfg cfg)
>> +{
>> +	if (dphy->ops->set_clk_lane_cfg)
>> +		dphy->ops->set_clk_lane_cfg(dphy, cfg);
>> +}
>> +
>> +static void cdns_dphy_set_pll_cfg(struct cdns_dphy *dphy,
>> +				  const struct cdns_dphy_cfg *cfg)
>> +{
>> +	if (dphy->ops->set_pll_cfg)
>> +		dphy->ops->set_pll_cfg(dphy, cfg);
>> +}
>> +
>> +static unsigned long cdns_dphy_get_wakeup_time_ns(struct cdns_dphy *dphy)
>> +{
>> +	return dphy->ops->get_wakeup_time_ns(dphy);
>> +}
>> +
>> +static unsigned long cdns_dphy_ref_get_wakeup_time_ns(struct cdns_dphy *dphy)
>> +{
>> +	/* Default wakeup time is 800 ns (in a simulated environment). */
>> +	return 800;
>> +}
>> +
>> +static void cdns_dphy_ref_set_pll_cfg(struct cdns_dphy *dphy,
>> +				      const struct cdns_dphy_cfg *cfg)
>> +{
>> +	u32 fbdiv_low, fbdiv_high;
>> +
>> +	fbdiv_low = (cfg->pll_fbdiv / 4) - 2;
>> +	fbdiv_high = cfg->pll_fbdiv - fbdiv_low - 2;
>> +
>> +	writel(DPHY_CMN_IPDIV_FROM_REG | DPHY_CMN_OPDIV_FROM_REG |
>> +	       DPHY_CMN_IPDIV(cfg->pll_ipdiv) |
>> +	       DPHY_CMN_OPDIV(cfg->pll_opdiv),
>> +	       dphy->regs + DPHY_CMN_OPIPDIV);
>> +	writel(DPHY_CMN_FBDIV_FROM_REG |
>> +	       DPHY_CMN_FBDIV_VAL(fbdiv_low, fbdiv_high),
>> +	       dphy->regs + DPHY_CMN_FBDIV);
>> +	writel(DPHY_CMN_PWM_HIGH(6) | DPHY_CMN_PWM_LOW(0x101) |
>> +	       DPHY_CMN_PWM_DIV(0x8),
>> +	       dphy->regs + DPHY_CMN_PWM);
>> +}
>> +
>> +static void cdns_dphy_ref_set_psm_div(struct cdns_dphy *dphy, u8 div)
>> +{
>> +	writel(DPHY_PSM_CFG_FROM_REG | DPHY_PSM_CLK_DIV(div),
>> +	       dphy->regs + DPHY_PSM_CFG);
>> +}
>> +
>> +/*
>> + * This is the reference implementation of DPHY hooks. Specific integration of
>> + * this IP may have to re-implement some of them depending on how they decided
>> + * to wire things in the SoC.
>> + */
>> +static const struct cdns_dphy_ops ref_dphy_ops = {
>> +	.get_wakeup_time_ns = cdns_dphy_ref_get_wakeup_time_ns,
>> +	.set_pll_cfg = cdns_dphy_ref_set_pll_cfg,
>> +	.set_psm_div = cdns_dphy_ref_set_psm_div,
>> +};
>> +
>> +static int cdns_dphy_config_from_opts(struct phy *phy,
>> +				      struct phy_configure_opts_mipi_dphy *opts,
>> +				      struct cdns_dphy_cfg *cfg)
>> +{
>> +	struct cdns_dphy *dphy = phy_get_drvdata(phy);
>> +	unsigned int dsi_hfp_ext = 0;
>> +	int ret;
>> +
>> +	ret = phy_mipi_dphy_config_validate(opts);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = cdns_dsi_get_dphy_pll_cfg(dphy, cfg,
>> +					opts, &dsi_hfp_ext);
>> +	if (ret)
>> +		return ret;
>> +
>> +	opts->wakeup = cdns_dphy_get_wakeup_time_ns(dphy);

Is the wakeup populated here used by the consumer driver?

Thanks
Kishon