[PATCH v2 2/5] clk: samsung: Fix clock disable failure because domain being gated

Krzysztof Kozlowski
2014-11-26T14:27:07Z

Audio subsystem clocks are located in separate block. If clock for this
block (from main clock domain) 'mau_epll' is gated then any read or
write to audss registers will block.

This was observed on Exynos 5420 platforms (Arndale Octa and Peach
Pi/Pit) after introducing runtime PM to pl330 DMA driver. After that
commit the 'mau_epll' was gated, because the "amba" clock was disabled
and there were no more users of mau_epll. The system hang on disabling
unused clocks from audss block.

Unfortunately the 'mau_epll' clock is not parent of some of audss clocks.

Whenever system wants to operate on audss clocks it has to enable epll
clock. The solution reuses common clk-gate/divider/mux code and duplicates
clk_register_*() functions. In the same time the patch tries to limit
functional changes of the driver so it does not fix minor issues with existing
code (like leaking memory allocated for clk-gate/clk-mux/clk-divider code).
This is addressed later.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reported-by: Kevin Hilman <khilman@kernel.org>
---
drivers/clk/samsung/clk-exynos-audss.c | 346 +++++++++++++++++++++++++++++----
1 file changed, 311 insertions(+), 35 deletions(-)

diff --git a/drivers/clk/samsung/clk-exynos-audss.c b/drivers/clk/samsung/clk-exynos-audss.c
index 7c4368e75ede..9ec7de866ab4 100644
--- a/drivers/clk/samsung/clk-exynos-audss.c
+++ b/drivers/clk/samsung/clk-exynos-audss.c
@@ -29,6 +29,7 @@ static DEFINE_SPINLOCK(lock);
static struct clk **clk_table;
static void __iomem *reg_base;
static struct clk_onecell_data clk_data;
+static struct clk *pll_in;

#define ASS_CLK_SRC 0x0
#define ASS_CLK_DIV 0x4
@@ -75,6 +76,276 @@ static const struct of_device_id exynos_audss_clk_of_match[] = {
{},
};

+static int pll_clk_enable(void)
+{
+ if (!IS_ERR(pll_in))
+ return clk_enable(pll_in);
+
+ return 0;
+}
+
+static void pll_clk_disable(void)
+{
+ if (!IS_ERR(pll_in))
+ clk_disable(pll_in);
+}
+
+static int audss_clk_gate_enable(struct clk_hw *hw)
+{
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret)
+ return ret;
+
+ ret = clk_gate_ops.enable(hw);
+
+ pll_clk_disable();
+
+ return ret;
+}
+
+static void audss_clk_gate_disable(struct clk_hw *hw)
+{
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret)
+ return;
+
+ clk_gate_ops.disable(hw);
+
+ pll_clk_disable();
+}
+
+static int audss_clk_gate_is_enabled(struct clk_hw *hw)
+{
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret)
+ return ret;
+
+ ret = clk_gate_ops.is_enabled(hw);
+
+ pll_clk_disable();
+
+ return ret;
+}
+
+static const struct clk_ops audss_clk_gate_ops = {
+ .enable = audss_clk_gate_enable,
+ .disable = audss_clk_gate_disable,
+ .is_enabled = audss_clk_gate_is_enabled,
+};
+
+/*
+ * A simplified copy of clk-gate.c:clk_register_gate() to mimic
+ * clk-gate behavior while using customized ops.
+ *
+ * TODO: just like clk-gate it leaks memory for struct clk_gate.
+ */
+static struct clk *audss_clk_register_gate(struct device *dev, const char *name,
+ const char *parent_name, unsigned long flags, u8 bit_idx)
+{
+ struct clk_gate *gate;
+ struct clk *clk;
+ struct clk_init_data init;
+
+ /* allocate the gate */
+ gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
+ if (!gate)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &audss_clk_gate_ops;
+ init.flags = flags | CLK_IS_BASIC;
+ init.parent_names = (parent_name ? &parent_name : NULL);
+ init.num_parents = (parent_name ? 1 : 0);
+
+ /* struct clk_gate assignments */
+ gate->reg = reg_base + ASS_CLK_GATE;
+ gate->bit_idx = bit_idx;
+ gate->flags = 0;
+ gate->lock = &lock;
+ gate->hw.init = &init;
+
+ clk = clk_register(dev, &gate->hw);
+
+ if (IS_ERR(clk))
+ kfree(gate);
+
+ return clk;
+}
+
+static unsigned long audss_clk_divider_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ unsigned long ret;
+
+ ret = pll_clk_enable();
+ if (ret) {
+ WARN(ret, "Could not enable pll_in clock\n");
+ return parent_rate;
+ }
+
+ ret = clk_divider_ops.recalc_rate(hw, parent_rate);
+
+ pll_clk_disable();
+
+ return ret;
+}
+
+static long audss_clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ return clk_divider_ops.round_rate(hw, rate, prate);
+}
+
+static int audss_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret)
+ return ret;
+
+ ret = clk_divider_ops.set_rate(hw, rate, parent_rate);
+
+ pll_clk_disable();
+
+ return ret;
+}
+
+static const struct clk_ops audss_clk_divider_ops = {
+ .recalc_rate = audss_clk_divider_recalc_rate,
+ .round_rate = audss_clk_divider_round_rate,
+ .set_rate = audss_clk_divider_set_rate,
+};
+
+/*
+ * A simplified copy of clk-divider.c:clk_register_divider() to mimic
+ * clk-divider behavior while using customized ops.
+ */
+static struct clk *audss_clk_register_divider(struct device *dev,
+ const char *name,
+ const char *parent_name, unsigned long flags,
+ u8 shift, u8 width)
+{
+ struct clk_divider *div;
+ struct clk *clk;
+ struct clk_init_data init;
+
+ /* allocate the divider */
+ div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
+ if (!div)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &audss_clk_divider_ops;
+ init.flags = flags | CLK_IS_BASIC;
+ init.parent_names = (parent_name ? &parent_name : NULL);
+ init.num_parents = (parent_name ? 1 : 0);
+
+ /* struct clk_divider assignments */
+ div->reg = reg_base + ASS_CLK_DIV;
+ div->shift = shift;
+ div->width = width;
+ div->flags = 0;
+ div->lock = &lock;
+ div->hw.init = &init;
+ div->table = NULL;
+
+ /* register the clock */
+ clk = clk_register(dev, &div->hw);
+
+ if (IS_ERR(clk))
+ kfree(div);
+
+ return clk;
+}
+
+static u8 audss_clk_mux_get_parent(struct clk_hw *hw)
+{
+ u8 parent;
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret) {
+ WARN(ret, "Could not enable pll_in clock\n");
+ return -EINVAL; /* Just like clk_mux_get_parent() */
+ }
+
+ parent = clk_mux_ops.get_parent(hw);
+
+ pll_clk_disable();
+
+ return parent;
+}
+
+static int audss_clk_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+ int ret;
+
+ ret = pll_clk_enable();
+ if (ret)
+ return ret;
+
+ ret = clk_mux_ops.set_parent(hw, index);
+
+ pll_clk_disable();
+
+ return ret;
+}
+
+static const struct clk_ops audss_clk_mux_ops = {
+ .get_parent = audss_clk_mux_get_parent,
+ .set_parent = audss_clk_mux_set_parent,
+ .determine_rate = __clk_mux_determine_rate,
+};
+
+/*
+ * A simplified copy of clk-mux.c:clk_register_mux_table() to mimic
+ * clk-mux behavior while using customized ops.
+ */
+static struct clk *audss_clk_register_mux(struct device *dev, const char *name,
+ const char **parent_names, u8 num_parents, unsigned long flags,
+ u8 shift, u8 width)
+{
+ struct clk_mux *mux;
+ struct clk *clk;
+ struct clk_init_data init;
+ u32 mask = BIT(width) - 1;
+
+ /* allocate the mux */
+ mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
+ if (!mux)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &audss_clk_mux_ops;
+ init.flags = flags | CLK_IS_BASIC;
+ init.parent_names = parent_names;
+ init.num_parents = num_parents;
+
+ /* struct clk_mux assignments */
+ mux->reg = reg_base + ASS_CLK_SRC;
+ mux->shift = shift;
+ mux->mask = mask;
+ mux->flags = 0;
+ mux->lock = &lock;
+ mux->table = NULL;
+ mux->hw.init = &init;
+
+ clk = clk_register(dev, &mux->hw);
+
+ if (IS_ERR(clk))
+ kfree(mux);
+
+ return clk;
+}
+
/* register exynos_audss clocks */
static int exynos_audss_clk_probe(struct platform_device *pdev)
{
@@ -83,7 +354,7 @@ static int exynos_audss_clk_probe(struct platform_device *pdev)
const char *mout_audss_p[] = {"fin_pll", "fout_epll"};
const char *mout_i2s_p[] = {"mout_audss", "cdclk0", "sclk_audio0"};
const char *sclk_pcm_p = "sclk_pcm0";
- struct clk *pll_ref, *pll_in, *cdclk, *sclk_audio, *sclk_pcm_in;
+ struct clk *pll_ref, *cdclk, *sclk_audio, *sclk_pcm_in;
const struct of_device_id *match;
enum exynos_audss_clk_type variant;

@@ -115,12 +386,21 @@ static int exynos_audss_clk_probe(struct platform_device *pdev)
pll_in = devm_clk_get(&pdev->dev, "pll_in");
if (!IS_ERR(pll_ref))
mout_audss_p[0] = __clk_get_name(pll_ref);
- if (!IS_ERR(pll_in))
+ if (!IS_ERR(pll_in)) {
mout_audss_p[1] = __clk_get_name(pll_in);
- clk_table[EXYNOS_MOUT_AUDSS] = clk_register_mux(NULL, "mout_audss",
+
+ ret = clk_prepare(pll_in);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "failed to prepare the pll_in clock\n");
+ return ret;
+ }
+
+ }
+
+ clk_table[EXYNOS_MOUT_AUDSS] = audss_clk_register_mux(NULL, "mout_audss",
mout_audss_p, ARRAY_SIZE(mout_audss_p),
- CLK_SET_RATE_NO_REPARENT,
- reg_base + ASS_CLK_SRC, 0, 1, 0, &lock);
+ CLK_SET_RATE_NO_REPARENT, 0, 1);

cdclk = devm_clk_get(&pdev->dev, "cdclk");
sclk_audio = devm_clk_get(&pdev->dev, "sclk_audio");
@@ -128,50 +408,40 @@ static int exynos_audss_clk_probe(struct platform_device *pdev)
mout_i2s_p[1] = __clk_get_name(cdclk);
if (!IS_ERR(sclk_audio))
mout_i2s_p[2] = __clk_get_name(sclk_audio);
- clk_table[EXYNOS_MOUT_I2S] = clk_register_mux(NULL, "mout_i2s",
+ clk_table[EXYNOS_MOUT_I2S] = audss_clk_register_mux(NULL, "mout_i2s",
mout_i2s_p, ARRAY_SIZE(mout_i2s_p),
- CLK_SET_RATE_NO_REPARENT,
- reg_base + ASS_CLK_SRC, 2, 2, 0, &lock);
+ CLK_SET_RATE_NO_REPARENT, 2, 2);

- clk_table[EXYNOS_DOUT_SRP] = clk_register_divider(NULL, "dout_srp",
- "mout_audss", 0, reg_base + ASS_CLK_DIV, 0, 4,
- 0, &lock);
+ clk_table[EXYNOS_DOUT_SRP] = audss_clk_register_divider(NULL, "dout_srp",
+ "mout_audss", 0, 0, 4);

- clk_table[EXYNOS_DOUT_AUD_BUS] = clk_register_divider(NULL,
- "dout_aud_bus", "dout_srp", 0,
- reg_base + ASS_CLK_DIV, 4, 4, 0, &lock);
+ clk_table[EXYNOS_DOUT_AUD_BUS] = audss_clk_register_divider(NULL,
+ "dout_aud_bus", "dout_srp", 0, 4, 4);

- clk_table[EXYNOS_DOUT_I2S] = clk_register_divider(NULL, "dout_i2s",
- "mout_i2s", 0, reg_base + ASS_CLK_DIV, 8, 4, 0,
- &lock);
+ clk_table[EXYNOS_DOUT_I2S] = audss_clk_register_divider(NULL, "dout_i2s",
+ "mout_i2s", 0, 8, 4);

- clk_table[EXYNOS_SRP_CLK] = clk_register_gate(NULL, "srp_clk",
- "dout_srp", CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 0, 0, &lock);
+ clk_table[EXYNOS_SRP_CLK] = audss_clk_register_gate(NULL, "srp_clk",
+ "dout_srp", CLK_SET_RATE_PARENT, 0);

- clk_table[EXYNOS_I2S_BUS] = clk_register_gate(NULL, "i2s_bus",
- "dout_aud_bus", CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 2, 0, &lock);
+ clk_table[EXYNOS_I2S_BUS] = audss_clk_register_gate(NULL, "i2s_bus",
+ "dout_aud_bus", CLK_SET_RATE_PARENT, 2);

- clk_table[EXYNOS_SCLK_I2S] = clk_register_gate(NULL, "sclk_i2s",
- "dout_i2s", CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 3, 0, &lock);
+ clk_table[EXYNOS_SCLK_I2S] = audss_clk_register_gate(NULL, "sclk_i2s",
+ "dout_i2s", CLK_SET_RATE_PARENT, 3);

- clk_table[EXYNOS_PCM_BUS] = clk_register_gate(NULL, "pcm_bus",
- "sclk_pcm", CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 4, 0, &lock);
+ clk_table[EXYNOS_PCM_BUS] = audss_clk_register_gate(NULL, "pcm_bus",
+ "sclk_pcm", CLK_SET_RATE_PARENT, 4);

sclk_pcm_in = devm_clk_get(&pdev->dev, "sclk_pcm_in");
if (!IS_ERR(sclk_pcm_in))
sclk_pcm_p = __clk_get_name(sclk_pcm_in);
- clk_table[EXYNOS_SCLK_PCM] = clk_register_gate(NULL, "sclk_pcm",
- sclk_pcm_p, CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 5, 0, &lock);
+ clk_table[EXYNOS_SCLK_PCM] = audss_clk_register_gate(NULL, "sclk_pcm",
+ sclk_pcm_p, CLK_SET_RATE_PARENT, 5);

if (variant == TYPE_EXYNOS5420) {
- clk_table[EXYNOS_ADMA] = clk_register_gate(NULL, "adma",
- "dout_srp", CLK_SET_RATE_PARENT,
- reg_base + ASS_CLK_GATE, 9, 0, &lock);
+ clk_table[EXYNOS_ADMA] = audss_clk_register_gate(NULL, "adma",
+ "dout_srp", CLK_SET_RATE_PARENT, 9);
}

for (i = 0; i < clk_data.clk_num; i++) {
@@ -198,6 +468,9 @@ static int exynos_audss_clk_probe(struct platform_device *pdev)
return 0;

unregister:
+ if (!IS_ERR(pll_in))
+ clk_unprepare(pll_in);
+
for (i = 0; i < clk_data.clk_num; i++) {
if (!IS_ERR(clk_table[i]))
clk_unregister(clk_table[i]);
@@ -214,6 +487,9 @@ static int exynos_audss_clk_remove(struct platform_device *pdev)
unregister_syscore_ops(&exynos_audss_clk_syscore_ops);
#endif

+ if (!IS_ERR(pll_in))
+ clk_unprepare(pll_in);
+
of_clk_del_provider(pdev->dev.of_node);

for (i = 0; i < clk_data.clk_num; i++) {
--
1.9.1