diff mbox series

[v3,1/8] clk: tegra20/30: Add custom EMC clock implementation

Message ID 20190524172353.29087-2-digetx@gmail.com
State Superseded
Headers show
Series memory: tegra: Introduce Tegra30 EMC driver | expand

Commit Message

Dmitry Osipenko May 24, 2019, 5:23 p.m. UTC 
A proper External Memory Controller clock rounding and parent selection
functionality is required by the EMC drivers. It is not available using
the generic clock implementation, hence add a custom one. The clock rate
rounding shall be done by the EMC drivers because they have information
about available memory timings, so the drivers will have to register a
callback that will round the requested rate. EMC clock users won't be able
to request EMC clock by getting -EPROBE_DEFER until EMC driver is probed
and the callback is set up. The functionality is somewhat similar to the
clk-emc.c which serves Tegra124+ SoC's, the later HW generations support
more parent clock sources and the HW configuration and integration with
the EMC drivers differs a tad from the older gens, hence it's not really
worth to try to squash everything into a single source file.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clk/tegra/Makefile          |   2 +
 drivers/clk/tegra/clk-tegra20-emc.c | 299 ++++++++++++++++++++++++++++
 drivers/clk/tegra/clk-tegra20.c     |  55 ++---
 drivers/clk/tegra/clk-tegra30.c     |  38 +++-
 drivers/clk/tegra/clk.h             |   6 +
 include/linux/clk/tegra.h           |  14 ++
 6 files changed, 362 insertions(+), 52 deletions(-)
 create mode 100644 drivers/clk/tegra/clk-tegra20-emc.c

Comments

Peter De Schrijver June 13, 2019, 10:49 a.m. UTC | #1 
On Fri, May 24, 2019 at 08:23:46PM +0300, Dmitry Osipenko wrote:
> A proper External Memory Controller clock rounding and parent selection
> functionality is required by the EMC drivers. It is not available using
> the generic clock implementation, hence add a custom one. The clock rate
> rounding shall be done by the EMC drivers because they have information
> about available memory timings, so the drivers will have to register a
> callback that will round the requested rate. EMC clock users won't be able
> to request EMC clock by getting -EPROBE_DEFER until EMC driver is probed
> and the callback is set up. The functionality is somewhat similar to the
> clk-emc.c which serves Tegra124+ SoC's, the later HW generations support
> more parent clock sources and the HW configuration and integration with
> the EMC drivers differs a tad from the older gens, hence it's not really
> worth to try to squash everything into a single source file.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clk/tegra/Makefile          |   2 +
>  drivers/clk/tegra/clk-tegra20-emc.c | 299 ++++++++++++++++++++++++++++
>  drivers/clk/tegra/clk-tegra20.c     |  55 ++---
>  drivers/clk/tegra/clk-tegra30.c     |  38 +++-
>  drivers/clk/tegra/clk.h             |   6 +
>  include/linux/clk/tegra.h           |  14 ++
>  6 files changed, 362 insertions(+), 52 deletions(-)
>  create mode 100644 drivers/clk/tegra/clk-tegra20-emc.c
> 
> diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
> index 4812e45c2214..df966ca06788 100644
> --- a/drivers/clk/tegra/Makefile
> +++ b/drivers/clk/tegra/Makefile
> @@ -17,7 +17,9 @@ obj-y					+= clk-tegra-fixed.o
>  obj-y					+= clk-tegra-super-gen4.o
>  obj-$(CONFIG_TEGRA_CLK_EMC)		+= clk-emc.o
>  obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += clk-tegra20.o
> +obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= clk-tegra20-emc.o
>  obj-$(CONFIG_ARCH_TEGRA_3x_SOC)         += clk-tegra30.o
> +obj-$(CONFIG_ARCH_TEGRA_3x_SOC)		+= clk-tegra20-emc.o
>  obj-$(CONFIG_ARCH_TEGRA_114_SOC)	+= clk-tegra114.o
>  obj-$(CONFIG_ARCH_TEGRA_124_SOC)	+= clk-tegra124.o
>  obj-$(CONFIG_TEGRA_CLK_DFLL)		+= clk-tegra124-dfll-fcpu.o
> diff --git a/drivers/clk/tegra/clk-tegra20-emc.c b/drivers/clk/tegra/clk-tegra20-emc.c
> new file mode 100644
> index 000000000000..d971b5425ce3
> --- /dev/null
> +++ b/drivers/clk/tegra/clk-tegra20-emc.c
> @@ -0,0 +1,299 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bits.h>
> +#include <linux/clk-provider.h>
> +#include <linux/clk/tegra.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +
> +#include "clk.h"
> +
> +#define CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK	GENMASK(7, 0)
> +#define CLK_SOURCE_EMC_2X_CLK_SRC_MASK		GENMASK(31, 30)
> +#define CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT		30
> +
> +#define MC_EMC_SAME_FREQ	BIT(16)
> +#define USE_PLLM_UD		BIT(29)
> +
> +#define EMC_SRC_PLL_M		0
> +#define EMC_SRC_PLL_C		1
> +#define EMC_SRC_PLL_P		2
> +#define EMC_SRC_CLK_M		3
> +
> +static const char * const emc_parent_clk_names[] = {
> +	"pll_m", "pll_c", "pll_p", "clk_m",
> +};
> +
> +struct tegra_clk_emc {
> +	struct clk_hw hw;
> +	void __iomem *reg;
> +	bool mc_same_freq;
> +	bool want_low_jitter;
> +
> +	tegra20_clk_emc_round_cb *round_cb;
> +	void *cb_arg;
> +};
> +
> +static inline struct tegra_clk_emc *to_tegra_clk_emc(struct clk_hw *hw)
> +{
> +	return container_of(hw, struct tegra_clk_emc, hw);
> +}
> +
> +static unsigned long emc_recalc_rate(struct clk_hw *hw,
> +				     unsigned long parent_rate)
> +{
> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
> +	u32 val, div;
> +
> +	val = readl_relaxed(emc->reg);
> +	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
> +
> +	return DIV_ROUND_UP(parent_rate * 2, div + 2);
> +}
> +
> +static u8 emc_get_parent(struct clk_hw *hw)
> +{
> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
> +
> +	return readl_relaxed(emc->reg) >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
> +}
> +
> +static int emc_set_parent(struct clk_hw *hw, u8 index)
> +{
> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
> +	u32 val, div;
> +
> +	val = readl_relaxed(emc->reg);
> +	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
> +	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
> +
> +	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
> +
> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
> +		val |= USE_PLLM_UD;
> +	else
> +		val &= ~USE_PLLM_UD;
> +
> +	if (emc->mc_same_freq)
> +		val |= MC_EMC_SAME_FREQ;
> +	else
> +		val &= ~MC_EMC_SAME_FREQ;
> +
> +	writel_relaxed(val, emc->reg);
> +

I think technically you need a fence_udelay(1) here, but in practice
this is probably not needed because you will poll some EMC register for
the frequency completion anyway. Maybe add a comment about this?

> +	return 0;
> +}
> +
> +static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
> +			unsigned long parent_rate)
> +{
> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
> +	unsigned int index;
> +	u32 val, div;
> +
> +	div = div_frac_get(rate, parent_rate, 8, 1, 0);
> +
> +	val = readl_relaxed(emc->reg);
> +	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
> +	val |= div;
> +
> +	index = val >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
> +
> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
> +		val |= USE_PLLM_UD;
> +	else
> +		val &= ~USE_PLLM_UD;
> +
> +	if (emc->mc_same_freq)
> +		val |= MC_EMC_SAME_FREQ;
> +	else
> +		val &= ~MC_EMC_SAME_FREQ;
> +
> +	writel_relaxed(val, emc->reg);
> +

Same here.

> +	return 0;
> +}
> +
> +static int emc_set_rate_and_parent(struct clk_hw *hw,
> +				   unsigned long rate,
> +				   unsigned long parent_rate,
> +				   u8 index)
> +{
> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
> +	u32 val, div;
> +
> +	div = div_frac_get(rate, parent_rate, 8, 1, 0);
> +
> +	val = readl_relaxed(emc->reg);
> +
> +	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
> +	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
> +
> +	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
> +	val |= div;
> +
> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
> +		val |= USE_PLLM_UD;
> +	else
> +		val &= ~USE_PLLM_UD;
> +
> +	if (emc->mc_same_freq)
> +		val |= MC_EMC_SAME_FREQ;
> +	else
> +		val &= ~MC_EMC_SAME_FREQ;
> +
> +	writel_relaxed(val, emc->reg);
> +

And here.

> +	return 0;
> +}

Peter.
Dmitry Osipenko June 13, 2019, 12:14 p.m. UTC | #2 
13.06.2019 13:49, Peter De Schrijver пишет:
> On Fri, May 24, 2019 at 08:23:46PM +0300, Dmitry Osipenko wrote:
>> A proper External Memory Controller clock rounding and parent selection
>> functionality is required by the EMC drivers. It is not available using
>> the generic clock implementation, hence add a custom one. The clock rate
>> rounding shall be done by the EMC drivers because they have information
>> about available memory timings, so the drivers will have to register a
>> callback that will round the requested rate. EMC clock users won't be able
>> to request EMC clock by getting -EPROBE_DEFER until EMC driver is probed
>> and the callback is set up. The functionality is somewhat similar to the
>> clk-emc.c which serves Tegra124+ SoC's, the later HW generations support
>> more parent clock sources and the HW configuration and integration with
>> the EMC drivers differs a tad from the older gens, hence it's not really
>> worth to try to squash everything into a single source file.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/clk/tegra/Makefile          |   2 +
>>  drivers/clk/tegra/clk-tegra20-emc.c | 299 ++++++++++++++++++++++++++++
>>  drivers/clk/tegra/clk-tegra20.c     |  55 ++---
>>  drivers/clk/tegra/clk-tegra30.c     |  38 +++-
>>  drivers/clk/tegra/clk.h             |   6 +
>>  include/linux/clk/tegra.h           |  14 ++
>>  6 files changed, 362 insertions(+), 52 deletions(-)
>>  create mode 100644 drivers/clk/tegra/clk-tegra20-emc.c
>>
>> diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
>> index 4812e45c2214..df966ca06788 100644
>> --- a/drivers/clk/tegra/Makefile
>> +++ b/drivers/clk/tegra/Makefile
>> @@ -17,7 +17,9 @@ obj-y					+= clk-tegra-fixed.o
>>  obj-y					+= clk-tegra-super-gen4.o
>>  obj-$(CONFIG_TEGRA_CLK_EMC)		+= clk-emc.o
>>  obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += clk-tegra20.o
>> +obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= clk-tegra20-emc.o
>>  obj-$(CONFIG_ARCH_TEGRA_3x_SOC)         += clk-tegra30.o
>> +obj-$(CONFIG_ARCH_TEGRA_3x_SOC)		+= clk-tegra20-emc.o
>>  obj-$(CONFIG_ARCH_TEGRA_114_SOC)	+= clk-tegra114.o
>>  obj-$(CONFIG_ARCH_TEGRA_124_SOC)	+= clk-tegra124.o
>>  obj-$(CONFIG_TEGRA_CLK_DFLL)		+= clk-tegra124-dfll-fcpu.o
>> diff --git a/drivers/clk/tegra/clk-tegra20-emc.c b/drivers/clk/tegra/clk-tegra20-emc.c
>> new file mode 100644
>> index 000000000000..d971b5425ce3
>> --- /dev/null
>> +++ b/drivers/clk/tegra/clk-tegra20-emc.c
>> @@ -0,0 +1,299 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include <linux/bits.h>
>> +#include <linux/clk-provider.h>
>> +#include <linux/clk/tegra.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/slab.h>
>> +
>> +#include "clk.h"
>> +
>> +#define CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK	GENMASK(7, 0)
>> +#define CLK_SOURCE_EMC_2X_CLK_SRC_MASK		GENMASK(31, 30)
>> +#define CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT		30
>> +
>> +#define MC_EMC_SAME_FREQ	BIT(16)
>> +#define USE_PLLM_UD		BIT(29)
>> +
>> +#define EMC_SRC_PLL_M		0
>> +#define EMC_SRC_PLL_C		1
>> +#define EMC_SRC_PLL_P		2
>> +#define EMC_SRC_CLK_M		3
>> +
>> +static const char * const emc_parent_clk_names[] = {
>> +	"pll_m", "pll_c", "pll_p", "clk_m",
>> +};
>> +
>> +struct tegra_clk_emc {
>> +	struct clk_hw hw;
>> +	void __iomem *reg;
>> +	bool mc_same_freq;
>> +	bool want_low_jitter;
>> +
>> +	tegra20_clk_emc_round_cb *round_cb;
>> +	void *cb_arg;
>> +};
>> +
>> +static inline struct tegra_clk_emc *to_tegra_clk_emc(struct clk_hw *hw)
>> +{
>> +	return container_of(hw, struct tegra_clk_emc, hw);
>> +}
>> +
>> +static unsigned long emc_recalc_rate(struct clk_hw *hw,
>> +				     unsigned long parent_rate)
>> +{
>> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
>> +	u32 val, div;
>> +
>> +	val = readl_relaxed(emc->reg);
>> +	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
>> +
>> +	return DIV_ROUND_UP(parent_rate * 2, div + 2);
>> +}
>> +
>> +static u8 emc_get_parent(struct clk_hw *hw)
>> +{
>> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
>> +
>> +	return readl_relaxed(emc->reg) >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
>> +}
>> +
>> +static int emc_set_parent(struct clk_hw *hw, u8 index)
>> +{
>> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
>> +	u32 val, div;
>> +
>> +	val = readl_relaxed(emc->reg);
>> +	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
>> +	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
>> +
>> +	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
>> +
>> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
>> +		val |= USE_PLLM_UD;
>> +	else
>> +		val &= ~USE_PLLM_UD;
>> +
>> +	if (emc->mc_same_freq)
>> +		val |= MC_EMC_SAME_FREQ;
>> +	else
>> +		val &= ~MC_EMC_SAME_FREQ;
>> +
>> +	writel_relaxed(val, emc->reg);
>> +
> 
> I think technically you need a fence_udelay(1) here, but in practice
> this is probably not needed because you will poll some EMC register for
> the frequency completion anyway. Maybe add a comment about this?
> 
>> +	return 0;
>> +}
>> +
>> +static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
>> +			unsigned long parent_rate)
>> +{
>> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
>> +	unsigned int index;
>> +	u32 val, div;
>> +
>> +	div = div_frac_get(rate, parent_rate, 8, 1, 0);
>> +
>> +	val = readl_relaxed(emc->reg);
>> +	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
>> +	val |= div;
>> +
>> +	index = val >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
>> +
>> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
>> +		val |= USE_PLLM_UD;
>> +	else
>> +		val &= ~USE_PLLM_UD;
>> +
>> +	if (emc->mc_same_freq)
>> +		val |= MC_EMC_SAME_FREQ;
>> +	else
>> +		val &= ~MC_EMC_SAME_FREQ;
>> +
>> +	writel_relaxed(val, emc->reg);
>> +
> 
> Same here.
> 
>> +	return 0;
>> +}
>> +
>> +static int emc_set_rate_and_parent(struct clk_hw *hw,
>> +				   unsigned long rate,
>> +				   unsigned long parent_rate,
>> +				   u8 index)
>> +{
>> +	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
>> +	u32 val, div;
>> +
>> +	div = div_frac_get(rate, parent_rate, 8, 1, 0);
>> +
>> +	val = readl_relaxed(emc->reg);
>> +
>> +	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
>> +	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
>> +
>> +	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
>> +	val |= div;
>> +
>> +	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
>> +		val |= USE_PLLM_UD;
>> +	else
>> +		val &= ~USE_PLLM_UD;
>> +
>> +	if (emc->mc_same_freq)
>> +		val |= MC_EMC_SAME_FREQ;
>> +	else
>> +		val &= ~MC_EMC_SAME_FREQ;
>> +
>> +	writel_relaxed(val, emc->reg);
>> +
> 
> And here.
> 
>> +	return 0;
>> +}
> 
> Peter.
> 

Thank you very much for the feedback! Indeed, it will be a bit more
robust to add fence_udelay() since one microsecond is practically
nothing and then it will be a part of the clk-change awaiting anyway
(note that EMC driver waits for the interrupt event and doesn't poll the
status), we also don't really care about the EMC rate-change performance
much because it won't happen frequently.
diff mbox series

Patch

diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
index 4812e45c2214..df966ca06788 100644
--- a/drivers/clk/tegra/Makefile
+++ b/drivers/clk/tegra/Makefile
@@ -17,7 +17,9 @@  obj-y					+= clk-tegra-fixed.o
 obj-y					+= clk-tegra-super-gen4.o
 obj-$(CONFIG_TEGRA_CLK_EMC)		+= clk-emc.o
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += clk-tegra20.o
+obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= clk-tegra20-emc.o
 obj-$(CONFIG_ARCH_TEGRA_3x_SOC)         += clk-tegra30.o
+obj-$(CONFIG_ARCH_TEGRA_3x_SOC)		+= clk-tegra20-emc.o
 obj-$(CONFIG_ARCH_TEGRA_114_SOC)	+= clk-tegra114.o
 obj-$(CONFIG_ARCH_TEGRA_124_SOC)	+= clk-tegra124.o
 obj-$(CONFIG_TEGRA_CLK_DFLL)		+= clk-tegra124-dfll-fcpu.o
diff --git a/drivers/clk/tegra/clk-tegra20-emc.c b/drivers/clk/tegra/clk-tegra20-emc.c
new file mode 100644
index 000000000000..d971b5425ce3
--- /dev/null
+++ b/drivers/clk/tegra/clk-tegra20-emc.c
@@ -0,0 +1,299 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bits.h>
+#include <linux/clk-provider.h>
+#include <linux/clk/tegra.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+#define CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK	GENMASK(7, 0)
+#define CLK_SOURCE_EMC_2X_CLK_SRC_MASK		GENMASK(31, 30)
+#define CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT		30
+
+#define MC_EMC_SAME_FREQ	BIT(16)
+#define USE_PLLM_UD		BIT(29)
+
+#define EMC_SRC_PLL_M		0
+#define EMC_SRC_PLL_C		1
+#define EMC_SRC_PLL_P		2
+#define EMC_SRC_CLK_M		3
+
+static const char * const emc_parent_clk_names[] = {
+	"pll_m", "pll_c", "pll_p", "clk_m",
+};
+
+struct tegra_clk_emc {
+	struct clk_hw hw;
+	void __iomem *reg;
+	bool mc_same_freq;
+	bool want_low_jitter;
+
+	tegra20_clk_emc_round_cb *round_cb;
+	void *cb_arg;
+};
+
+static inline struct tegra_clk_emc *to_tegra_clk_emc(struct clk_hw *hw)
+{
+	return container_of(hw, struct tegra_clk_emc, hw);
+}
+
+static unsigned long emc_recalc_rate(struct clk_hw *hw,
+				     unsigned long parent_rate)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+	u32 val, div;
+
+	val = readl_relaxed(emc->reg);
+	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+
+	return DIV_ROUND_UP(parent_rate * 2, div + 2);
+}
+
+static u8 emc_get_parent(struct clk_hw *hw)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+
+	return readl_relaxed(emc->reg) >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+}
+
+static int emc_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+	u32 val, div;
+
+	val = readl_relaxed(emc->reg);
+	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
+	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+	div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+
+	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+		val |= USE_PLLM_UD;
+	else
+		val &= ~USE_PLLM_UD;
+
+	if (emc->mc_same_freq)
+		val |= MC_EMC_SAME_FREQ;
+	else
+		val &= ~MC_EMC_SAME_FREQ;
+
+	writel_relaxed(val, emc->reg);
+
+	return 0;
+}
+
+static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long parent_rate)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+	unsigned int index;
+	u32 val, div;
+
+	div = div_frac_get(rate, parent_rate, 8, 1, 0);
+
+	val = readl_relaxed(emc->reg);
+	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+	val |= div;
+
+	index = val >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+		val |= USE_PLLM_UD;
+	else
+		val &= ~USE_PLLM_UD;
+
+	if (emc->mc_same_freq)
+		val |= MC_EMC_SAME_FREQ;
+	else
+		val &= ~MC_EMC_SAME_FREQ;
+
+	writel_relaxed(val, emc->reg);
+
+	return 0;
+}
+
+static int emc_set_rate_and_parent(struct clk_hw *hw,
+				   unsigned long rate,
+				   unsigned long parent_rate,
+				   u8 index)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+	u32 val, div;
+
+	div = div_frac_get(rate, parent_rate, 8, 1, 0);
+
+	val = readl_relaxed(emc->reg);
+
+	val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
+	val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+	val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+	val |= div;
+
+	if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+		val |= USE_PLLM_UD;
+	else
+		val &= ~USE_PLLM_UD;
+
+	if (emc->mc_same_freq)
+		val |= MC_EMC_SAME_FREQ;
+	else
+		val &= ~MC_EMC_SAME_FREQ;
+
+	writel_relaxed(val, emc->reg);
+
+	return 0;
+}
+
+static int emc_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+	struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+	struct clk_hw *parent_hw;
+	unsigned long divided_rate;
+	unsigned long parent_rate;
+	unsigned int i;
+	long emc_rate;
+	int div;
+
+	emc_rate = emc->round_cb(req->rate, req->min_rate, req->max_rate,
+				 emc->cb_arg);
+	if (emc_rate < 0)
+		return emc_rate;
+
+	for (i = 0; i < ARRAY_SIZE(emc_parent_clk_names); i++) {
+		parent_hw = clk_hw_get_parent_by_index(hw, i);
+
+		if (req->best_parent_hw == parent_hw)
+			parent_rate = req->best_parent_rate;
+		else
+			parent_rate = clk_hw_get_rate(parent_hw);
+
+		if (emc_rate > parent_rate)
+			continue;
+
+		div = div_frac_get(emc_rate, parent_rate, 8, 1, 0);
+		divided_rate = DIV_ROUND_UP(parent_rate * 2, div + 2);
+
+		if (divided_rate != emc_rate)
+			continue;
+
+		req->best_parent_rate = parent_rate;
+		req->best_parent_hw = parent_hw;
+		req->rate = emc_rate;
+		break;
+	}
+
+	if (i == ARRAY_SIZE(emc_parent_clk_names)) {
+		pr_err_once("%s: can't find parent for rate %lu emc_rate %lu\n",
+			    __func__, req->rate, emc_rate);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct clk_ops tegra_clk_emc_ops = {
+	.recalc_rate = emc_recalc_rate,
+	.get_parent = emc_get_parent,
+	.set_parent = emc_set_parent,
+	.set_rate = emc_set_rate,
+	.set_rate_and_parent = emc_set_rate_and_parent,
+	.determine_rate = emc_determine_rate,
+};
+
+void tegra20_clk_set_emc_round_callback(tegra20_clk_emc_round_cb *round_cb,
+					void *cb_arg)
+{
+	struct clk *clk = __clk_lookup("emc");
+	struct tegra_clk_emc *emc;
+	struct clk_hw *hw;
+
+	if (clk) {
+		hw = __clk_get_hw(clk);
+		emc = to_tegra_clk_emc(hw);
+
+		emc->round_cb = round_cb;
+		emc->cb_arg = cb_arg;
+	}
+}
+
+bool tegra20_clk_emc_driver_available(struct clk_hw *emc_hw)
+{
+	return to_tegra_clk_emc(emc_hw)->round_cb != NULL;
+}
+
+struct clk *tegra20_clk_register_emc(void __iomem *ioaddr)
+{
+	struct tegra_clk_emc *emc;
+	struct clk_init_data init;
+	struct clk *clk;
+
+	emc = kzalloc(sizeof(*emc), GFP_KERNEL);
+	if (!emc)
+		return NULL;
+
+	init.name = "emc";
+	init.ops = &tegra_clk_emc_ops;
+	init.flags = CLK_IS_CRITICAL;
+	init.parent_names = emc_parent_clk_names;
+	init.num_parents = ARRAY_SIZE(emc_parent_clk_names);
+
+	emc->reg = ioaddr;
+	emc->hw.init = &init;
+
+	clk = clk_register(NULL, &emc->hw);
+	if (IS_ERR(clk)) {
+		kfree(emc);
+		return NULL;
+	}
+
+	return clk;
+}
+
+void tegra30_clk_set_emc_round_callback(tegra30_clk_emc_round_cb *round_cb,
+					void *cb_arg)
+{
+	tegra20_clk_set_emc_round_callback(round_cb, cb_arg);
+}
+
+bool tegra30_clk_emc_driver_available(struct clk_hw *emc_hw)
+{
+	return tegra20_clk_emc_driver_available(emc_hw);
+}
+
+struct clk *tegra30_clk_register_emc(void __iomem *ioaddr)
+{
+	struct tegra_clk_emc *emc;
+	struct clk_hw *hw;
+	struct clk *clk;
+
+	clk = tegra20_clk_register_emc(ioaddr);
+	if (!clk)
+		return NULL;
+
+	hw = __clk_get_hw(clk);
+	emc = to_tegra_clk_emc(hw);
+	emc->want_low_jitter = true;
+
+	return clk;
+}
+
+int tegra30_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same)
+{
+	struct tegra_clk_emc *emc;
+	struct clk_hw *hw;
+
+	if (emc_clk) {
+		hw = __clk_get_hw(emc_clk);
+		emc = to_tegra_clk_emc(hw);
+		emc->mc_same_freq = same;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index c71b61162a32..1c5b8923f2be 100644
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -141,8 +141,6 @@  static struct cpu_clk_suspend_context {
 static void __iomem *clk_base;
 static void __iomem *pmc_base;
 
-static DEFINE_SPINLOCK(emc_lock);
-
 #define TEGRA_INIT_DATA_MUX(_name, _parents, _offset,	\
 			    _clk_num, _gate_flags, _clk_id)	\
 	TEGRA_INIT_DATA(_name, NULL, NULL, _parents, _offset,	\
@@ -771,7 +769,6 @@  static const char *pwm_parents[] = { "pll_p", "pll_c", "audio", "clk_m",
 static const char *mux_pllpcm_clkm[] = { "pll_p", "pll_c", "pll_m", "clk_m" };
 static const char *mux_pllpdc_clkm[] = { "pll_p", "pll_d_out0", "pll_c",
 					 "clk_m" };
-static const char *mux_pllmcp_clkm[] = { "pll_m", "pll_c", "pll_p", "clk_m" };
 
 static struct tegra_periph_init_data tegra_periph_clk_list[] = {
 	TEGRA_INIT_DATA_MUX("i2s1", i2s1_parents,     CLK_SOURCE_I2S1,   11, TEGRA_PERIPH_ON_APB, TEGRA20_CLK_I2S1),
@@ -798,41 +795,6 @@  static struct tegra_periph_init_data tegra_periph_nodiv_clk_list[] = {
 	TEGRA_INIT_DATA_NODIV("disp2",	mux_pllpdc_clkm, CLK_SOURCE_DISP2, 30, 2, 26,  0, TEGRA20_CLK_DISP2),
 };
 
-static void __init tegra20_emc_clk_init(void)
-{
-	const u32 use_pllm_ud = BIT(29);
-	struct clk *clk;
-	u32 emc_reg;
-
-	clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
-			       ARRAY_SIZE(mux_pllmcp_clkm),
-			       CLK_SET_RATE_NO_REPARENT,
-			       clk_base + CLK_SOURCE_EMC,
-			       30, 2, 0, &emc_lock);
-
-	clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
-				    &emc_lock);
-	clks[TEGRA20_CLK_MC] = clk;
-
-	/* un-divided pll_m_out0 is currently unsupported */
-	emc_reg = readl_relaxed(clk_base + CLK_SOURCE_EMC);
-	if (emc_reg & use_pllm_ud) {
-		pr_err("%s: un-divided PllM_out0 used as clock source\n",
-		       __func__);
-		return;
-	}
-
-	/*
-	 * Note that 'emc_mux' source and 'emc' rate shouldn't be changed at
-	 * the same time due to a HW bug, this won't happen because we're
-	 * defining 'emc_mux' and 'emc' as distinct clocks.
-	 */
-	clk = tegra_clk_register_divider("emc", "emc_mux",
-				clk_base + CLK_SOURCE_EMC, CLK_IS_CRITICAL,
-				TEGRA_DIVIDER_INT, 0, 8, 1, &emc_lock);
-	clks[TEGRA20_CLK_EMC] = clk;
-}
-
 static void __init tegra20_periph_clk_init(void)
 {
 	struct tegra_periph_init_data *data;
@@ -846,7 +808,13 @@  static void __init tegra20_periph_clk_init(void)
 	clks[TEGRA20_CLK_AC97] = clk;
 
 	/* emc */
-	tegra20_emc_clk_init();
+	clk = tegra20_clk_register_emc(clk_base + CLK_SOURCE_EMC);
+
+	clks[TEGRA20_CLK_EMC] = clk;
+
+	clk = tegra_clk_register_mc("mc", "emc", clk_base + CLK_SOURCE_EMC,
+				    NULL);
+	clks[TEGRA20_CLK_MC] = clk;
 
 	/* dsi */
 	clk = tegra_clk_register_periph_gate("dsi", "pll_d", 0, clk_base, 0,
@@ -1126,6 +1094,8 @@  static struct clk *tegra20_clk_src_onecell_get(struct of_phandle_args *clkspec,
 	if (IS_ERR(clk))
 		return clk;
 
+	hw = __clk_get_hw(clk);
+
 	/*
 	 * Tegra20 CDEV1 and CDEV2 clocks are a bit special case, their parent
 	 * clock is created by the pinctrl driver. It is possible for clk user
@@ -1135,13 +1105,16 @@  static struct clk *tegra20_clk_src_onecell_get(struct of_phandle_args *clkspec,
 	 */
 	if (clkspec->args[0] == TEGRA20_CLK_CDEV1 ||
 	    clkspec->args[0] == TEGRA20_CLK_CDEV2) {
-		hw = __clk_get_hw(clk);
-
 		parent_hw = clk_hw_get_parent(hw);
 		if (!parent_hw)
 			return ERR_PTR(-EPROBE_DEFER);
 	}
 
+	if (clkspec->args[0] == TEGRA20_CLK_EMC) {
+		if (!tegra20_clk_emc_driver_available(hw))
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
 	return clk;
 }
 
diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c
index fa8d573ac626..2b69ad4aa259 100644
--- a/drivers/clk/tegra/clk-tegra30.c
+++ b/drivers/clk/tegra/clk-tegra30.c
@@ -162,7 +162,6 @@  static unsigned long input_freq;
 
 static DEFINE_SPINLOCK(cml_lock);
 static DEFINE_SPINLOCK(pll_d_lock);
-static DEFINE_SPINLOCK(emc_lock);
 
 #define TEGRA_INIT_DATA_MUX(_name, _parents, _offset,	\
 			    _clk_num, _gate_flags, _clk_id)	\
@@ -819,7 +818,7 @@  static struct tegra_clk tegra30_clks[tegra_clk_max] __initdata = {
 	[tegra_clk_pll_a] = { .dt_id = TEGRA30_CLK_PLL_A, .present = true },
 	[tegra_clk_pll_a_out0] = { .dt_id = TEGRA30_CLK_PLL_A_OUT0, .present = true },
 	[tegra_clk_cec] = { .dt_id = TEGRA30_CLK_CEC, .present = true },
-	[tegra_clk_emc] = { .dt_id = TEGRA30_CLK_EMC, .present = true },
+	[tegra_clk_emc] = { .dt_id = TEGRA30_CLK_EMC, .present = false },
 };
 
 static const char *pll_e_parents[] = { "pll_ref", "pll_p" };
@@ -1006,7 +1005,6 @@  static void __init tegra30_super_clk_init(void)
 static const char *mux_pllacp_clkm[] = { "pll_a_out0", "unused", "pll_p",
 					 "clk_m" };
 static const char *mux_pllpcm_clkm[] = { "pll_p", "pll_c", "pll_m", "clk_m" };
-static const char *mux_pllmcp_clkm[] = { "pll_m", "pll_c", "pll_p", "clk_m" };
 static const char *spdif_out_parents[] = { "pll_a_out0", "spdif_2x", "pll_p",
 					   "clk_m" };
 static const char *mux_pllmcpa[] = { "pll_m", "pll_c", "pll_p", "pll_a_out0" };
@@ -1055,14 +1053,12 @@  static void __init tegra30_periph_clk_init(void)
 	clks[TEGRA30_CLK_AFI] = clk;
 
 	/* emc */
-	clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
-			       ARRAY_SIZE(mux_pllmcp_clkm),
-			       CLK_SET_RATE_NO_REPARENT,
-			       clk_base + CLK_SOURCE_EMC,
-			       30, 2, 0, &emc_lock);
+	clk = tegra30_clk_register_emc(clk_base + CLK_SOURCE_EMC);
+
+	clks[TEGRA30_CLK_EMC] = clk;
 
-	clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
-				    &emc_lock);
+	clk = tegra_clk_register_mc("mc", "emc", clk_base + CLK_SOURCE_EMC,
+				    NULL);
 	clks[TEGRA30_CLK_MC] = clk;
 
 	/* cml0 */
@@ -1313,6 +1309,26 @@  static struct tegra_audio_clk_info tegra30_audio_plls[] = {
 	{ "pll_a", &pll_a_params, tegra_clk_pll_a, "pll_p_out1" },
 };
 
+static struct clk *tegra30_clk_src_onecell_get(struct of_phandle_args *clkspec,
+					       void *data)
+{
+	struct clk_hw *hw;
+	struct clk *clk;
+
+	clk = of_clk_src_onecell_get(clkspec, data);
+	if (IS_ERR(clk))
+		return clk;
+
+	hw = __clk_get_hw(clk);
+
+	if (clkspec->args[0] == TEGRA30_CLK_EMC) {
+		if (!tegra30_clk_emc_driver_available(hw))
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	return clk;
+}
+
 static void __init tegra30_clock_init(struct device_node *np)
 {
 	struct device_node *node;
@@ -1356,7 +1372,7 @@  static void __init tegra30_clock_init(struct device_node *np)
 
 	tegra_init_dup_clks(tegra_clk_duplicates, clks, TEGRA30_CLK_CLK_MAX);
 
-	tegra_add_of_provider(np, of_clk_src_onecell_get);
+	tegra_add_of_provider(np, tegra30_clk_src_onecell_get);
 	tegra_register_devclks(devclks, ARRAY_SIZE(devclks));
 
 	tegra_clk_apply_init_table = tegra30_clock_apply_init_table;
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 09bccbb9640c..8c94d71f48f7 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -849,4 +849,10 @@  int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
 		udelay(delay);		\
 	} while (0)
 
+bool tegra20_clk_emc_driver_available(struct clk_hw *emc_hw);
+struct clk *tegra20_clk_register_emc(void __iomem *ioaddr);
+
+bool tegra30_clk_emc_driver_available(struct clk_hw *emc_hw);
+struct clk *tegra30_clk_register_emc(void __iomem *ioaddr);
+
 #endif /* TEGRA_CLK_H */
diff --git a/include/linux/clk/tegra.h b/include/linux/clk/tegra.h
index afb9edfa5d58..ec65046504f7 100644
--- a/include/linux/clk/tegra.h
+++ b/include/linux/clk/tegra.h
@@ -130,4 +130,18 @@  extern void tegra210_put_utmipll_in_iddq(void);
 extern void tegra210_put_utmipll_out_iddq(void);
 extern int tegra210_clk_handle_mbist_war(unsigned int id);
 
+struct clk;
+
+typedef long (tegra20_clk_emc_round_cb)(unsigned long rate,
+					unsigned long min_rate,
+					unsigned long max_rate,
+					void *arg);
+#define tegra30_clk_emc_round_cb	tegra20_clk_emc_round_cb
+
+void tegra20_clk_set_emc_round_callback(tegra20_clk_emc_round_cb *round_cb,
+					void *cb_arg);
+void tegra30_clk_set_emc_round_callback(tegra30_clk_emc_round_cb *round_cb,
+					void *cb_arg);
+int tegra30_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same);
+
 #endif /* __LINUX_CLK_TEGRA_H_ */