Message-ID: <56CAF4DE.2060708@ti.com>
Date:	Mon, 22 Feb 2016 17:15:34 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Heiko Stuebner <heiko@...ech.de>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-rockchip@...ts.infradead.org>, <arnd@...db.de>,
	<romain.perier@...il.com>
Subject: Re: [PATCH v5.1] phy: rockchip-usb: add handler for usb-uart
 functionality

Hi,

On Monday 22 February 2016 05:11 PM, Heiko Stuebner wrote:
> Most newer Rockchip SoCs provide the possibility to use a usb-phy
> as passthrough for the debug uart (uart2), making it possible to
> for example get console output without needing to open the device.
> 
> This patch adds an early_initcall to enable this functionality
> conditionally via the commandline and also disables the corresponding
> usb controller in the devicetree.
> 
> Currently only data for the rk3288 is provided, but at least the
> rk3188 and arm64 rk3368 also provide this functionality and will be
> enabled later.
> 
> On a spliced usb cable the signals are tx on white wire(D+) and
> rx on green wire(D-).
> 
> The one caveat is that currently the reconfiguration of the phy
> happens as early_initcall, as the code depends on the unflattened
> devicetree being available. Everything is fine if only a regular
> console is active as the console-replay will happen after the
> reconfiguation. But with earlycon active output up to smp-init
> currently will get lost.
> 
> The phy is an optional property for the connected dwc2 controller,
> so we still provide the phy device but fail all phy-ops with -EBUSY
> to make sure the dwc2 does not try to transmit anything on the
> repurposed phy.
> 
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
> changes in v5.1:
> - fix corruptions that happened when sending v5

I still see the corruption.

This is how I see the patch after downloading (from both mutt and thunderbird)
@@ -3486,6 +3486,12 @@ bytes respectively. Such letter suffixes can also be=
 entirely omitted.
=20
        ro              [KNL] Mount root device read-only on boot
=20
+       rockchip.usb_uart
+                       Enable the uart passthrough on the designated usb port
+                       on Rockchip SoCs. When active, the signals of the
+                       debug-uart get routed to the D+ and D- pins of the usb
+                       port and the regular usb controller gets disabled.
+
        root=3D         [KNL] Root filesystem
                        See name_to_dev_t comment in init/do_mounts.c.
=20
diff --git a/drivers/phy/phy-rockchip-usb.c b/drivers/phy/phy-rockchip-usb.=
c
index 33a80eb..f62d899 100644
--- a/drivers/phy/phy-rockchip-usb.c
+++ b/drivers/phy/phy-rockchip-usb.c
@@ -30,21 +30,23 @@
 #include <linux/regmap.h>
 #include <linux/mfd/syscon.h>
=20
-/*
- * The higher 16-bit of this register is used for write protection
- * only if BIT(13 + 16) set to 1 the BIT(13) can be written.
- */
-#define SIDDQ_WRITE_ENA        BIT(29)
-#define SIDDQ_ON               BIT(13)
-#define SIDDQ_OFF              (0 << 13)
+static int enable_usb_uart;
+
+#define HIWORD_UPDATE(val, mask) \
+               ((val) | (mask) << 16)
+
+#define UOC_CON0_SIDDQ BIT(13)
=20
 struct rockchip_usb_phys {
        int reg;
        const char *pll_name;
 };
=20
<snip>
.
.

I didn't see this problem with the other patches I applied today.

Thanks
Kishon

> changes in v5:
> - only compile debug uart functionality if the phy is compiled in
>   fixes initcall conflict and debug functionality also is only really
>   usable if it's available early
> changes in v4:
> - drop the rest of the phy-series, as the patches have gotten applied
> 
> So far, this hasn't gotten eyeballs yet, so citing discussion-parts from
> the v3 coverletter:
> 
> The patch, while not associated with the new pll handling, also builds
> on the groundwork introduced there and adds support for the function
> repurposing one of the phys as passthrough for uart-data. This enables
> attaching a ttl converter to the D+ and D- pins of an usb cable to
> receive uart data this way, when it is not really possible to attach
> a regular serial console to a board.
> 
> One point of critique in my first iteration [0] of this was, that
> due to when the reconfiguration happens we may miss parts of the logs
> when earlycon is enabled. So far early_initcall gets used as the
> unflattened devicetree is necessary to set this up. Doing this for
> example in the early_param directly would require parsing the flattened
> devicetree to get needed nodes and properties.
> 
> I still maintain that if you're working on anything before smp-bringup
> you should use a real dev-board instead or try to solder uart cables
> on hopefully available test-points  .
> 
> 
>  Documentation/kernel-parameters.txt |   6 +
>  drivers/phy/phy-rockchip-usb.c      | 233 ++++++++++++++++++++++++++++++------
>  2 files changed, 203 insertions(+), 36 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 87d40a7..d91417b 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -3486,6 +3486,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  
>  	ro		[KNL] Mount root device read-only on boot
>  
> +	rockchip.usb_uart
> +			Enable the uart passthrough on the designated usb port
> +			on Rockchip SoCs. When active, the signals of the
> +			debug-uart get routed to the D+ and D- pins of the usb
> +			port and the regular usb controller gets disabled.
> +
>  	root=		[KNL] Root filesystem
>  			See name_to_dev_t comment in init/do_mounts.c.
>  
> diff --git a/drivers/phy/phy-rockchip-usb.c b/drivers/phy/phy-rockchip-usb.c
> index 33a80eb..f62d899 100644
> --- a/drivers/phy/phy-rockchip-usb.c
> +++ b/drivers/phy/phy-rockchip-usb.c
> @@ -30,21 +30,23 @@
>  #include <linux/regmap.h>
>  #include <linux/mfd/syscon.h>
>  
> -/*
> - * The higher 16-bit of this register is used for write protection
> - * only if BIT(13 + 16) set to 1 the BIT(13) can be written.
> - */
> -#define SIDDQ_WRITE_ENA	BIT(29)
> -#define SIDDQ_ON		BIT(13)
> -#define SIDDQ_OFF		(0 << 13)
> +static int enable_usb_uart;
> +
> +#define HIWORD_UPDATE(val, mask) \
> +		((val) | (mask) << 16)
> +
> +#define UOC_CON0_SIDDQ BIT(13)
>  
>  struct rockchip_usb_phys {
>  	int reg;
>  	const char *pll_name;
>  };
>  
> +struct rockchip_usb_phy_base;
>  struct rockchip_usb_phy_pdata {
>  	struct rockchip_usb_phys *phys;
> +	int (*init_usb_uart)(struct regmap *grf);
> +	int usb_uart_phy;
>  };
>  
>  struct rockchip_usb_phy_base {
> @@ -61,13 +63,15 @@ struct rockchip_usb_phy {
>  	struct clk      *clk480m;
>  	struct clk_hw	clk480m_hw;
>  	struct phy	*phy;
> +	bool		uart_enabled;
>  };
>  
>  static int rockchip_usb_phy_power(struct rockchip_usb_phy *phy,
>  					   bool siddq)
>  {
> -	return regmap_write(phy->base->reg_base, phy->reg_offset,
> -			    SIDDQ_WRITE_ENA | (siddq ? SIDDQ_ON : SIDDQ_OFF));
> +	u32 val = HIWORD_UPDATE(siddq ? UOC_CON0_SIDDQ : 0, UOC_CON0_SIDDQ);
> +
> +	return regmap_write(phy->base->reg_base, phy->reg_offset, val);
>  }
>  
>  static unsigned long rockchip_usb_phy480m_recalc_rate(struct clk_hw *hw,
> @@ -108,7 +112,7 @@ static int rockchip_usb_phy480m_is_enabled(struct clk_hw *hw)
>  	if (ret < 0)
>  		return ret;
>  
> -	return (val & SIDDQ_ON) ? 0 : 1;
> +	return (val & UOC_CON0_SIDDQ) ? 0 : 1;
>  }
>  
>  static const struct clk_ops rockchip_usb_phy480m_ops = {
> @@ -122,6 +126,9 @@ static int rockchip_usb_phy_power_off(struct phy *_phy)
>  {
>  	struct rockchip_usb_phy *phy = phy_get_drvdata(_phy);
>  
> +	if (phy->uart_enabled)
> +		return -EBUSY;
> +
>  	clk_disable_unprepare(phy->clk480m);
>  
>  	return 0;
> @@ -131,6 +138,9 @@ static int rockchip_usb_phy_power_on(struct phy *_phy)
>  {
>  	struct rockchip_usb_phy *phy = phy_get_drvdata(_phy);
>  
> +	if (phy->uart_enabled)
> +		return -EBUSY;
> +
>  	return clk_prepare_enable(phy->clk480m);
>  }
>  
> @@ -144,8 +154,10 @@ static void rockchip_usb_phy_action(void *data)
>  {
>  	struct rockchip_usb_phy *rk_phy = data;
>  
> -	of_clk_del_provider(rk_phy->np);
> -	clk_unregister(rk_phy->clk480m);
> +	if (!rk_phy->uart_enabled) {
> +		of_clk_del_provider(rk_phy->np);
> +		clk_unregister(rk_phy->clk480m);
> +	}
>  
>  	if (rk_phy->clk)
>  		clk_put(rk_phy->clk);
> @@ -194,30 +206,35 @@ static int rockchip_usb_phy_init(struct rockchip_usb_phy_base *base,
>  		return -EINVAL;
>  	}
>  
> -	if (rk_phy->clk) {
> -		clk_name = __clk_get_name(rk_phy->clk);
> -		init.flags = 0;
> -		init.parent_names = &clk_name;
> -		init.num_parents = 1;
> +	if (enable_usb_uart && base->pdata->usb_uart_phy == i) {
> +		dev_dbg(base->dev, "phy%d used as uart output\n", i);
> +		rk_phy->uart_enabled = true;
>  	} else {
> -		init.flags = CLK_IS_ROOT;
> -		init.parent_names = NULL;
> -		init.num_parents = 0;
> -	}
> +		if (rk_phy->clk) {
> +			clk_name = __clk_get_name(rk_phy->clk);
> +			init.flags = 0;
> +			init.parent_names = &clk_name;
> +			init.num_parents = 1;
> +		} else {
> +			init.flags = CLK_IS_ROOT;
> +			init.parent_names = NULL;
> +			init.num_parents = 0;
> +		}
>  
> -	init.ops = &rockchip_usb_phy480m_ops;
> -	rk_phy->clk480m_hw.init = &init;
> +		init.ops = &rockchip_usb_phy480m_ops;
> +		rk_phy->clk480m_hw.init = &init;
>  
> -	rk_phy->clk480m = clk_register(base->dev, &rk_phy->clk480m_hw);
> -	if (IS_ERR(rk_phy->clk480m)) {
> -		err = PTR_ERR(rk_phy->clk480m);
> -		goto err_clk;
> -	}
> +		rk_phy->clk480m = clk_register(base->dev, &rk_phy->clk480m_hw);
> +		if (IS_ERR(rk_phy->clk480m)) {
> +			err = PTR_ERR(rk_phy->clk480m);
> +			goto err_clk;
> +		}
>  
> -	err = of_clk_add_provider(child, of_clk_src_simple_get,
> -				  rk_phy->clk480m);
> -	if (err < 0)
> -		goto err_clk_prov;
> +		err = of_clk_add_provider(child, of_clk_src_simple_get,
> +					rk_phy->clk480m);
> +		if (err < 0)
> +			goto err_clk_prov;
> +	}
>  
>  	err = devm_add_action(base->dev, rockchip_usb_phy_action, rk_phy);
>  	if (err)
> @@ -230,13 +247,21 @@ static int rockchip_usb_phy_init(struct rockchip_usb_phy_base *base,
>  	}
>  	phy_set_drvdata(rk_phy->phy, rk_phy);
>  
> -	/* only power up usb phy when it use, so disable it when init*/
> -	return rockchip_usb_phy_power(rk_phy, 1);
> +	/*
> +	 * When acting as uart-pipe, just keep clock on otherwise
> +	 * only power up usb phy when it use, so disable it when init
> +	 */
> +	if (rk_phy->uart_enabled)
> +		return clk_prepare_enable(rk_phy->clk);
> +	else
> +		return rockchip_usb_phy_power(rk_phy, 1);
>  
>  err_devm_action:
> -	of_clk_del_provider(child);
> +	if (!rk_phy->uart_enabled)
> +		of_clk_del_provider(child);
>  err_clk_prov:
> -	clk_unregister(rk_phy->clk480m);
> +	if (!rk_phy->uart_enabled)
> +		clk_unregister(rk_phy->clk480m);
>  err_clk:
>  	if (rk_phy->clk)
>  		clk_put(rk_phy->clk);
> @@ -259,6 +284,86 @@ static const struct rockchip_usb_phy_pdata rk3188_pdata = {
>  	},
>  };
>  
> +#define RK3288_UOC0_CON0				0x320
> +#define RK3288_UOC0_CON0_COMMON_ON_N			BIT(0)
> +#define RK3288_UOC0_CON0_DISABLE			BIT(4)
> +
> +#define RK3288_UOC0_CON2				0x328
> +#define RK3288_UOC0_CON2_SOFT_CON_SEL			BIT(2)
> +
> +#define RK3288_UOC0_CON3				0x32c
> +#define RK3288_UOC0_CON3_UTMI_SUSPENDN			BIT(0)
> +#define RK3288_UOC0_CON3_UTMI_OPMODE_NODRIVING		(1 << 1)
> +#define RK3288_UOC0_CON3_UTMI_OPMODE_MASK		(3 << 1)
> +#define RK3288_UOC0_CON3_UTMI_XCVRSEELCT_FSTRANSC	(1 << 3)
> +#define RK3288_UOC0_CON3_UTMI_XCVRSEELCT_MASK		(3 << 3)
> +#define RK3288_UOC0_CON3_UTMI_TERMSEL_FULLSPEED		BIT(5)
> +#define RK3288_UOC0_CON3_BYPASSDMEN			BIT(6)
> +#define RK3288_UOC0_CON3_BYPASSSEL			BIT(7)
> +
> +/*
> + * Enable the bypass of uart2 data through the otg usb phy.
> + * Original description in the TRM.
> + * 1. Disable the OTG block by setting OTGDISABLE0 to 1’b1.
> + * 2. Disable the pull-up resistance on the D+ line by setting
> + *    OPMODE0[1:0] to 2’b01.
> + * 3. To ensure that the XO, Bias, and PLL blocks are powered down in Suspend
> + *    mode, set COMMONONN to 1’b1.
> + * 4. Place the USB PHY in Suspend mode by setting SUSPENDM0 to 1’b0.
> + * 5. Set BYPASSSEL0 to 1’b1.
> + * 6. To transmit data, controls BYPASSDMEN0, and BYPASSDMDATA0.
> + * To receive data, monitor FSVPLUS0.
> + *
> + * The actual code in the vendor kernel does some things differently.
> + */
> +static int __init rk3288_init_usb_uart(struct regmap *grf)
> +{
> +	u32 val;
> +	int ret;
> +
> +	/*
> +	 * COMMON_ON and DISABLE settings are described in the TRM,
> +	 * but were not present in the original code.
> +	 * Also disable the analog phy components to save power.
> +	 */
> +	val = HIWORD_UPDATE(RK3288_UOC0_CON0_COMMON_ON_N
> +				| RK3288_UOC0_CON0_DISABLE
> +				| UOC_CON0_SIDDQ,
> +			    RK3288_UOC0_CON0_COMMON_ON_N
> +				| RK3288_UOC0_CON0_DISABLE
> +				| UOC_CON0_SIDDQ);
> +	ret = regmap_write(grf, RK3288_UOC0_CON0, val);
> +	if (ret)
> +		return ret;
> +
> +	val = HIWORD_UPDATE(RK3288_UOC0_CON2_SOFT_CON_SEL,
> +			    RK3288_UOC0_CON2_SOFT_CON_SEL);
> +	ret = regmap_write(grf, RK3288_UOC0_CON2, val);
> +	if (ret)
> +		return ret;
> +
> +	val = HIWORD_UPDATE(RK3288_UOC0_CON3_UTMI_OPMODE_NODRIVING
> +				| RK3288_UOC0_CON3_UTMI_XCVRSEELCT_FSTRANSC
> +				| RK3288_UOC0_CON3_UTMI_TERMSEL_FULLSPEED,
> +			    RK3288_UOC0_CON3_UTMI_SUSPENDN
> +				| RK3288_UOC0_CON3_UTMI_OPMODE_MASK
> +				| RK3288_UOC0_CON3_UTMI_XCVRSEELCT_MASK
> +				| RK3288_UOC0_CON3_UTMI_TERMSEL_FULLSPEED);
> +	ret = regmap_write(grf, RK3288_UOC0_CON3, val);
> +	if (ret)
> +		return ret;
> +
> +	val = HIWORD_UPDATE(RK3288_UOC0_CON3_BYPASSSEL
> +				| RK3288_UOC0_CON3_BYPASSDMEN,
> +			    RK3288_UOC0_CON3_BYPASSSEL
> +				| RK3288_UOC0_CON3_BYPASSDMEN);
> +	ret = regmap_write(grf, RK3288_UOC0_CON3, val);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  static const struct rockchip_usb_phy_pdata rk3288_pdata = {
>  	.phys = (struct rockchip_usb_phys[]){
>  		{ .reg = 0x320, .pll_name = "sclk_otgphy0_480m" },
> @@ -266,6 +371,8 @@ static const struct rockchip_usb_phy_pdata rk3288_pdata = {
>  		{ .reg = 0x348, .pll_name = "sclk_otgphy2_480m" },
>  		{ /* sentinel */ }
>  	},
> +	.init_usb_uart = rk3288_init_usb_uart,
> +	.usb_uart_phy = 0,
>  };
>  
>  static int rockchip_usb_phy_probe(struct platform_device *pdev)
> @@ -328,6 +435,60 @@ static struct platform_driver rockchip_usb_driver = {
>  
>  module_platform_driver(rockchip_usb_driver);
>  
> +#ifndef MODULE
> +static int __init rockchip_init_usb_uart(void)
> +{
> +	const struct of_device_id *match;
> +	const struct rockchip_usb_phy_pdata *data;
> +	struct device_node *np;
> +	struct regmap *grf;
> +	int ret;
> +
> +	if (!enable_usb_uart)
> +		return 0;
> +
> +	np = of_find_matching_node_and_match(NULL, rockchip_usb_phy_dt_ids,
> +					     &match);
> +	if (!np) {
> +		pr_err("%s: failed to find usbphy node\n", __func__);
> +		return -ENOTSUPP;
> +	}
> +
> +	pr_debug("%s: using settings for %s\n", __func__, match->compatible);
> +	data = match->data;
> +
> +	if (!data->init_usb_uart) {
> +		pr_err("%s: usb-uart not available on %s\n",
> +		       __func__, match->compatible);
> +		return -ENOTSUPP;
> +	}
> +
> +	grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
> +	if (IS_ERR(grf)) {
> +		pr_err("%s: Missing rockchip,grf property, %lu\n",
> +		       __func__, PTR_ERR(grf));
> +		return PTR_ERR(grf);
> +	}
> +
> +	ret = data->init_usb_uart(grf);
> +	if (ret) {
> +		pr_err("%s: could not init usb_uart, %d\n", __func__, ret);
> +		enable_usb_uart = 0;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +early_initcall(rockchip_init_usb_uart);
> +
> +static int __init rockchip_usb_uart(char *buf)
> +{
> +	enable_usb_uart = true;
> +	return 0;
> +}
> +early_param("rockchip.usb_uart", rockchip_usb_uart);
> +#endif
> +
>  MODULE_AUTHOR("Yunzhi Li <lyz@...k-chips.com>");
>  MODULE_DESCRIPTION("Rockchip USB 2.0 PHY driver");
>  MODULE_LICENSE("GPL v2");
> 

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