| Message ID | 20170714064302.20383-3-wens@csie.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
Hi, On Fri, Jul 14, 2017 at 02:42:53PM +0800, Chen-Yu Tsai wrote: > Starting with the A83T SoC, Allwinner introduced a new timing mode for > its MMC clocks. The new mode changes how the MMC controller sample and > output clocks are delayed to match chip and board specifics. There are > two controls for this, one on the CCU side controlling how the clocks > behave, and one in the MMC controller controlling what inputs to take > and how to route them. > > In the old mode, the MMC clock had 2 child clocks providing the output > and sample clocks, which could be delayed by a number of clock cycles > measured from the MMC clock's parent. > > With the new mode, the 2 delay clocks are no longer active. Instead, > the delays and associated controls are moved into the MMC controller. > The output of the MMC clock is also halved. > > The difference in how things are wired between the modes means that the > clock controls and the MMC controls must match. To achieve this in a > clear, explicit way, we introduce two functions for the MMC driver to > use: one queries the hardware for the current mode set, and the other > allows the MMC driver to request a mode. > > With newer SoCs such as the A64, the old mode is all but removed. Hence > we support two variations, one where the mode can be toggled, and the > other where the clock is fixed in the new mode. > > Signed-off-by: Chen-Yu Tsai <wens@csie.org> > --- > drivers/clk/sunxi-ng/Makefile | 1 + > drivers/clk/sunxi-ng/ccu_common.h | 2 + > drivers/clk/sunxi-ng/ccu_mmc_timing.c | 73 +++++++++++++++++++++++++++++++++++ > include/linux/clk/sunxi-ng.h | 20 ++++++++++ > 4 files changed, 96 insertions(+) > create mode 100644 drivers/clk/sunxi-ng/ccu_mmc_timing.c > create mode 100644 include/linux/clk/sunxi-ng.h > > diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile > index 0c45fa50283d..45a5910379a5 100644 > --- a/drivers/clk/sunxi-ng/Makefile > +++ b/drivers/clk/sunxi-ng/Makefile > @@ -1,5 +1,6 @@ > # Common objects > lib-$(CONFIG_SUNXI_CCU) += ccu_common.o > +lib-$(CONFIG_SUNXI_CCU) += ccu_mmc_timing.o > lib-$(CONFIG_SUNXI_CCU) += ccu_reset.o > > # Base clock types > diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h > index d6fdd7a789aa..88981e7fd978 100644 > --- a/drivers/clk/sunxi-ng/ccu_common.h > +++ b/drivers/clk/sunxi-ng/ccu_common.h > @@ -23,6 +23,8 @@ > #define CCU_FEATURE_FIXED_POSTDIV BIT(3) > #define CCU_FEATURE_ALL_PREDIV BIT(4) > #define CCU_FEATURE_LOCK_REG BIT(5) > +#define CCU_FEATURE_MMC_TIMING_SWITCH BIT(6) > +#define CCU_FEATURE_MMC_ALWAYS_NEW BIT(7) I'm not really sure we need the ALWAYS_NEW bit here. In the case where the clocks cannot operate in the old mode any more, we won't even query the clocks, since we know that it's not needed at all. Pretty much just like what we're doing for old-mode-only clocks at the moment. I guess the only thing we should indentify is whether the clock can switch between the two, or not, and the MMC_TIMING_SWITCH bit is already perfect for that. Maxime
diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile index 0c45fa50283d..45a5910379a5 100644 --- a/drivers/clk/sunxi-ng/Makefile +++ b/drivers/clk/sunxi-ng/Makefile @@ -1,5 +1,6 @@ # Common objects lib-$(CONFIG_SUNXI_CCU) += ccu_common.o +lib-$(CONFIG_SUNXI_CCU) += ccu_mmc_timing.o lib-$(CONFIG_SUNXI_CCU) += ccu_reset.o # Base clock types diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h index d6fdd7a789aa..88981e7fd978 100644 --- a/drivers/clk/sunxi-ng/ccu_common.h +++ b/drivers/clk/sunxi-ng/ccu_common.h @@ -23,6 +23,8 @@ #define CCU_FEATURE_FIXED_POSTDIV BIT(3) #define CCU_FEATURE_ALL_PREDIV BIT(4) #define CCU_FEATURE_LOCK_REG BIT(5) +#define CCU_FEATURE_MMC_TIMING_SWITCH BIT(6) +#define CCU_FEATURE_MMC_ALWAYS_NEW BIT(7) struct device_node; diff --git a/drivers/clk/sunxi-ng/ccu_mmc_timing.c b/drivers/clk/sunxi-ng/ccu_mmc_timing.c new file mode 100644 index 000000000000..f236a56abf48 --- /dev/null +++ b/drivers/clk/sunxi-ng/ccu_mmc_timing.c @@ -0,0 +1,73 @@ +/* + * Copyright (c) 2017 Chen-Yu Tsai. All rights reserved. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/clk-provider.h> +#include <linux/clk/sunxi-ng.h> + +#include "ccu_common.h" + +#define CCU_MMC_NEW_TIMING_MODE BIT(30) + +/** + * sunxi_ccu_set_mmc_timing_mode: Configure the MMC clock timing mode + * @clk: clock to be configured + * @new_mode: true for new timing mode introduced in A83T and later + * + * Returns 0 on success, -ENOTSUPP if the clock does not support + * switching modes. + */ +int sunxi_ccu_set_mmc_timing_mode(struct clk *clk, bool new_mode) +{ + struct clk_hw *hw = __clk_get_hw(clk); + struct ccu_common *cm = hw_to_ccu_common(hw); + unsigned long flags; + u32 val; + + if (!(cm->features & CCU_FEATURE_MMC_TIMING_SWITCH)) + return -ENOTSUPP; + + spin_lock_irqsave(cm->lock, flags); + + val = readl(cm->base + cm->reg); + if (new_mode) + val |= CCU_MMC_NEW_TIMING_MODE; + else + val &= ~CCU_MMC_NEW_TIMING_MODE; + writel(val, cm->base + cm->reg); + + spin_unlock_irqrestore(cm->lock, flags); + + return 0; +} + +/** + * sunxi_ccu_set_mmc_timing_mode: Get the current MMC clock timing mode + * @clk: clock to query + * + * Returns 0 if the clock is in old timing mode, > 0 if it is in + * new timing mode, and -ENOTSUPP if the clock does not support + * this function. + */ +int sunxi_ccu_get_mmc_timing_mode(struct clk *clk) +{ + struct clk_hw *hw = __clk_get_hw(clk); + struct ccu_common *cm = hw_to_ccu_common(hw); + + if (cm->features & CCU_FEATURE_MMC_ALWAYS_NEW) + return 1; + + if (!(cm->features & CCU_FEATURE_MMC_TIMING_SWITCH)) + return -ENOTSUPP; + + return !!(readl(cm->base + cm->reg) & CCU_MMC_NEW_TIMING_MODE); +} diff --git a/include/linux/clk/sunxi-ng.h b/include/linux/clk/sunxi-ng.h new file mode 100644 index 000000000000..f1bd321fc264 --- /dev/null +++ b/include/linux/clk/sunxi-ng.h @@ -0,0 +1,20 @@ +/* + * Copyright (c) 2017 Chen-Yu Tsai. All rights reserved. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#ifndef _LINUX_CLK_SUNXI_NG_H_ +#define _LINUX_CLK_SUNXI_NG_H_ + +int sunxi_ccu_set_mmc_timing_mode(struct clk *clk, bool new_mode); +int sunxi_ccu_get_mmc_timing_mode(struct clk *clk); + +#endif
Starting with the A83T SoC, Allwinner introduced a new timing mode for its MMC clocks. The new mode changes how the MMC controller sample and output clocks are delayed to match chip and board specifics. There are two controls for this, one on the CCU side controlling how the clocks behave, and one in the MMC controller controlling what inputs to take and how to route them. In the old mode, the MMC clock had 2 child clocks providing the output and sample clocks, which could be delayed by a number of clock cycles measured from the MMC clock's parent. With the new mode, the 2 delay clocks are no longer active. Instead, the delays and associated controls are moved into the MMC controller. The output of the MMC clock is also halved. The difference in how things are wired between the modes means that the clock controls and the MMC controls must match. To achieve this in a clear, explicit way, we introduce two functions for the MMC driver to use: one queries the hardware for the current mode set, and the other allows the MMC driver to request a mode. With newer SoCs such as the A64, the old mode is all but removed. Hence we support two variations, one where the mode can be toggled, and the other where the clock is fixed in the new mode. Signed-off-by: Chen-Yu Tsai <wens@csie.org> --- drivers/clk/sunxi-ng/Makefile | 1 + drivers/clk/sunxi-ng/ccu_common.h | 2 + drivers/clk/sunxi-ng/ccu_mmc_timing.c | 73 +++++++++++++++++++++++++++++++++++ include/linux/clk/sunxi-ng.h | 20 ++++++++++ 4 files changed, 96 insertions(+) create mode 100644 drivers/clk/sunxi-ng/ccu_mmc_timing.c create mode 100644 include/linux/clk/sunxi-ng.h