[PATCH v3 02/10] clk: sunxi-ng: Add MP_MMC clocks that support MMC timing modes switching

Chen-Yu Tsai
2017-07-24T13:59:47Z

All of our MMC clocks are of the MP clock type. A few MMC clocks on some
SoCs, such as MMC2 on the A83T, support new/old timing mode switching.

>From a clock rate point of view, when the new timing mode is active. the
output clock rate is halved.

This patch adds a special wrapper class of clocks, MP_MMC, around the
generic MP type clocks. The rate related callbacks in ccu_mp_mmc_ops
for this class look at the timing mode bit and apply the /2 post-divider
when needed, before passing it through to the generic class ops,
ccu_mp_ops.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
drivers/clk/sunxi-ng/ccu_mp.c | 80 +++++++++++++++++++++++++++++++++++++++++++
drivers/clk/sunxi-ng/ccu_mp.h | 30 ++++++++++++++++
2 files changed, 110 insertions(+)

diff --git a/drivers/clk/sunxi-ng/ccu_mp.c b/drivers/clk/sunxi-ng/ccu_mp.c
index b917ad7a386c..688855e7dc8c 100644
--- a/drivers/clk/sunxi-ng/ccu_mp.c
+++ b/drivers/clk/sunxi-ng/ccu_mp.c
@@ -172,3 +172,83 @@ const struct clk_ops ccu_mp_ops = {
.recalc_rate = ccu_mp_recalc_rate,
.set_rate = ccu_mp_set_rate,
};
+
+/*
+ * Support for MMC timing mode switching
+ *
+ * The MMC clocks on some SoCs support switching between old and
+ * new timing modes. A platform specific API is provided to query
+ * and set the timing mode on supported SoCs.
+ *
+ * In addition, a special class of ccu_mp_ops is provided, which
+ * takes in to account the timing mode switch. When the new timing
+ * mode is active, the clock output rate is halved. This new class
+ * is a wrapper around the generic ccu_mp_ops. When clock rates
+ * are passed through to ccu_mp_ops callbacks, they are doubled
+ * if the new timing mode bit is set, to account for the post
+ * divider. Conversely, when clock rates are passed back, they
+ * are halved if the mode bit is set.
+ */
+
+static unsigned long ccu_mp_mmc_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ unsigned long rate = ccu_mp_recalc_rate(hw, parent_rate);
+ struct ccu_common *cm = hw_to_ccu_common(hw);
+ u32 val = readl(cm->base + cm->reg);
+
+ if (val & CCU_MMC_NEW_TIMING_MODE)
+ return rate / 2;
+ return rate;
+}
+
+static int ccu_mp_mmc_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+{
+ struct ccu_common *cm = hw_to_ccu_common(hw);
+ u32 val = readl(cm->base + cm->reg);
+ int ret;
+
+ /* adjust the requested clock rate */
+ if (val & CCU_MMC_NEW_TIMING_MODE) {
+ req->rate *= 2;
+ req->min_rate *= 2;
+ req->max_rate *= 2;
+ }
+
+ ret = ccu_mp_determine_rate(hw, req);
+
+ /* re-adjust the requested clock rate back */
+ if (val & CCU_MMC_NEW_TIMING_MODE) {
+ req->rate /= 2;
+ req->min_rate /= 2;
+ req->max_rate /= 2;
+ }
+
+ return ret;
+}
+
+static int ccu_mp_mmc_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct ccu_common *cm = hw_to_ccu_common(hw);
+ u32 val = readl(cm->base + cm->reg);
+
+ if (val & CCU_MMC_NEW_TIMING_MODE)
+ rate *= 2;
+
+ return ccu_mp_set_rate(hw, rate, parent_rate);
+}
+
+const struct clk_ops ccu_mp_mmc_ops = {
+ .disable = ccu_mp_disable,
+ .enable = ccu_mp_enable,
+ .is_enabled = ccu_mp_is_enabled,
+
+ .get_parent = ccu_mp_get_parent,
+ .set_parent = ccu_mp_set_parent,
+
+ .determine_rate = ccu_mp_mmc_determine_rate,
+ .recalc_rate = ccu_mp_mmc_recalc_rate,
+ .set_rate = ccu_mp_mmc_set_rate,
+};
diff --git a/drivers/clk/sunxi-ng/ccu_mp.h b/drivers/clk/sunxi-ng/ccu_mp.h
index 915625e97d98..aaef11d747ea 100644
--- a/drivers/clk/sunxi-ng/ccu_mp.h
+++ b/drivers/clk/sunxi-ng/ccu_mp.h
@@ -14,6 +14,7 @@
#ifndef _CCU_MP_H_
#define _CCU_MP_H_

+#include <linux/bitops.h>
#include <linux/clk-provider.h>

#include "ccu_common.h"
@@ -74,4 +75,33 @@ static inline struct ccu_mp *hw_to_ccu_mp(struct clk_hw *hw)

extern const struct clk_ops ccu_mp_ops;

+/*
+ * Special class of M-P clock that supports MMC timing modes
+ *
+ * Since the MMC clock registers all follow the same layout, we can
+ * simplify the macro for this particular case. In addition, as
+ * switching modes also affects the output clock rate, we need to
+ * have CLK_GET_RATE_NOCACHE for all these types of clocks.
+ */
+
+#define SUNXI_CCU_MP_MMC_WITH_MUX_GATE(_struct, _name, _parents, _reg, \
+ _flags) \
+ struct ccu_mp _struct = { \
+ .enable = BIT(31), \
+ .m = _SUNXI_CCU_DIV(0, 4), \
+ .p = _SUNXI_CCU_DIV(16, 2), \
+ .mux = _SUNXI_CCU_MUX(24, 2), \
+ .common = { \
+ .reg = _reg, \
+ .features = CCU_FEATURE_MMC_TIMING_SWITCH, \
+ .hw.init = CLK_HW_INIT_PARENTS(_name, \
+ _parents, \
+ &ccu_mp_mmc_ops, \
+ CLK_GET_RATE_NOCACHE | \
+ _flags), \
+ } \
+ }
+
+extern const struct clk_ops ccu_mp_mmc_ops;
+
#endif /* _CCU_MP_H_ */
--
2.13.3