[PATCH 3/3] spi: meson-axg: add a linear clock divider support
Yixun Lan
yixun.lan at amlogic.com
Thu May 3 14:36:44 PDT 2018
From: Sunny Luo <sunny.luo at amlogic.com>
The SPICC controller in Meson-AXG SoC is capable of using
a linear clock divider to reach a much fine tuned range of clocks,
while the old controller only use a power of two clock divider,
result at a more coarse clock range.
Also convert the clock registeration into Common Clock Framework.
Signed-off-by: Sunny Luo <sunny.luo at amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan at amlogic.com>
---
drivers/spi/spi-meson-spicc.c | 209 +++++++++++++++++++++++++++-------
1 file changed, 169 insertions(+), 40 deletions(-)
diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
index 90b15f7d50dd..e8389d7e62e5 100644
--- a/drivers/spi/spi-meson-spicc.c
+++ b/drivers/spi/spi-meson-spicc.c
@@ -116,6 +116,9 @@
#define SPICC_DWADDR 0x24 /* Write Address of DMA */
#define SPICC_ENH_CTL0 0x38 /* Enhanced Feature */
+#define SPICC_ENH_CLK_CS_DELAY_MASK GENMASK(15, 0)
+#define SPICC_ENH_DATARATE_MASK GENMASK(23, 16)
+#define SPICC_ENH_DATARATE_EN BIT(24)
#define SPICC_ENH_MOSI_OEN BIT(25)
#define SPICC_ENH_CLK_OEN BIT(26)
#define SPICC_ENH_CS_OEN BIT(27)
@@ -131,6 +134,7 @@
struct meson_spicc_data {
unsigned int max_speed_hz;
bool has_oen;
+ bool has_enhance_clk_div;
};
struct meson_spicc_device {
@@ -138,6 +142,7 @@ struct meson_spicc_device {
struct platform_device *pdev;
void __iomem *base;
struct clk *core;
+ struct clk *clk;
struct spi_message *message;
struct spi_transfer *xfer;
const struct meson_spicc_data *data;
@@ -325,40 +330,6 @@ static irqreturn_t meson_spicc_irq(int irq, void *data)
return IRQ_HANDLED;
}
-static u32 meson_spicc_setup_speed(struct meson_spicc_device *spicc, u32 conf,
- u32 speed)
-{
- unsigned long parent, value;
- unsigned int i, div;
-
- parent = clk_get_rate(spicc->core);
-
- /* Find closest inferior/equal possible speed */
- for (i = 0 ; i < 7 ; ++i) {
- /* 2^(data_rate+2) */
- value = parent >> (i + 2);
-
- if (value <= speed)
- break;
- }
-
- /* If provided speed it lower than max divider, use max divider */
- if (i > 7) {
- div = 7;
- dev_warn_once(&spicc->pdev->dev, "unable to get close to speed %u\n",
- speed);
- } else
- div = i;
-
- dev_dbg(&spicc->pdev->dev, "parent %lu, speed %u -> %lu (%u)\n",
- parent, speed, value, div);
-
- conf &= ~SPICC_DATARATE_MASK;
- conf |= FIELD_PREP(SPICC_DATARATE_MASK, div);
-
- return conf;
-}
-
static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
struct spi_transfer *xfer)
{
@@ -367,9 +338,6 @@ static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
/* Read original configuration */
conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG);
- /* Select closest divider */
- conf = meson_spicc_setup_speed(spicc, conf, xfer->speed_hz);
-
/* Setup word width */
conf &= ~SPICC_BITLENGTH_MASK;
conf |= FIELD_PREP(SPICC_BITLENGTH_MASK,
@@ -378,6 +346,8 @@ static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
/* Ignore if unchanged */
if (conf != conf_orig)
writel_relaxed(conf, spicc->base + SPICC_CONREG);
+
+ clk_set_rate(spicc->clk, xfer->speed_hz);
}
static int meson_spicc_transfer_one(struct spi_master *master,
@@ -486,9 +456,6 @@ static int meson_spicc_unprepare_transfer(struct spi_master *master)
/* Disable all IRQs */
writel(0, spicc->base + SPICC_INTREG);
- /* Disable controller */
- writel_bits_relaxed(SPICC_ENABLE, 0, spicc->base + SPICC_CONREG);
-
device_reset_optional(&spicc->pdev->dev);
return 0;
@@ -528,6 +495,157 @@ static void meson_spicc_cleanup(struct spi_device *spi)
spi->controller_state = NULL;
}
+/*
+ * The Clock Mux
+ * x-----------------x x------------x x------\
+ * |---| 0) fixed factor |---| 1) old div |----| |
+ * | x-----------------x x------------x | |
+ * src ---| |5) mux|-- out
+ * | x-----------------x x------------x | |
+ * |---| 2) fixed factor |---| 3) new div |0---| |
+ * x-----------------x x------------x x------/
+ *
+ * Clk path for GX series:
+ * src -> 0 -> 1 -> out
+ *
+ * Clk path for AXG series:
+ * src -> 0 -> 1 -> 5 -> out
+ * src -> 2 -> 3 -> 5 -> out
+ */
+
+/* algorithm for div0 + div1: rate = freq / 4 / (2 ^ N) */
+static struct clk_fixed_factor meson_spicc_div0 = {
+ .mult = 1,
+ .div = 4,
+};
+
+static struct clk_divider meson_spicc_div1 = {
+ .reg = (void *) SPICC_CONREG,
+ .shift = 16,
+ .width = 3,
+ .flags = CLK_DIVIDER_POWER_OF_TWO,
+};
+
+/* algorithm for div2 + div3: rate = freq / 2 / (N + 1) */
+static struct clk_fixed_factor meson_spicc_div2 = {
+ .mult = 1,
+ .div = 2,
+};
+
+static struct clk_divider meson_spicc_div3 = {
+ .reg = (void *) SPICC_ENH_CTL0,
+ .shift = 16,
+ .width = 8,
+};
+
+static struct clk_mux meson_spicc_sel = {
+ .reg = (void *) SPICC_ENH_CTL0,
+ .mask = 0x1,
+ .shift = 24,
+};
+
+static int meson_spicc_clk_init(struct meson_spicc_device *spicc)
+{
+ struct device *dev = &spicc->pdev->dev;
+ struct clk_fixed_factor *div0;
+ struct clk_divider *div1;
+ struct clk_mux *mux;
+ struct clk_init_data init;
+ struct clk *clk;
+ const char *parent_names[1];
+ const char *mux_parent_names[2];
+ char name[32];
+
+ div0 = &meson_spicc_div0;
+ snprintf(name, sizeof(name), "%s#_div0", dev_name(dev));
+ init.name = name;
+ init.ops = &clk_fixed_factor_ops;
+ init.flags = 0;
+ parent_names[0] = __clk_get_name(spicc->core);
+ init.parent_names = parent_names;
+ init.num_parents = 1;
+
+ div0->hw.init = &init;
+
+ clk = devm_clk_register(dev, &div0->hw);
+ if (WARN_ON(IS_ERR(clk)))
+ return PTR_ERR(clk);
+
+ div1 = &meson_spicc_div1;
+ snprintf(name, sizeof(name), "%s#_div1", dev_name(dev));
+ init.name = name;
+ init.ops = &clk_divider_ops;
+ init.flags = CLK_SET_RATE_PARENT;
+ parent_names[0] = __clk_get_name(clk);
+ init.parent_names = parent_names;
+ init.num_parents = 1;
+
+ div1->reg = spicc->base + (u64) div1->reg;
+ div1->hw.init = &init;
+
+ clk = devm_clk_register(dev, &div1->hw);
+ if (WARN_ON(IS_ERR(clk)))
+ return PTR_ERR(clk);
+
+ if (spicc->data->has_enhance_clk_div == false) {
+ spicc->clk = clk;
+ return 0;
+ }
+
+ mux_parent_names[0] = __clk_get_name(clk);
+
+ div0 = &meson_spicc_div2;
+ snprintf(name, sizeof(name), "%s#_div2", dev_name(dev));
+ init.name = name;
+ init.ops = &clk_fixed_factor_ops;
+ init.flags = 0;
+ parent_names[0] = __clk_get_name(spicc->core);
+ init.parent_names = parent_names;
+ init.num_parents = 1;
+
+ div0->hw.init = &init;
+
+ clk = devm_clk_register(dev, &div0->hw);
+ if (WARN_ON(IS_ERR(clk)))
+ return PTR_ERR(clk);
+
+ div1 = &meson_spicc_div3;
+ snprintf(name, sizeof(name), "%s#_div3", dev_name(dev));
+ init.name = name;
+ init.ops = &clk_divider_ops;
+ init.flags = CLK_SET_RATE_PARENT;
+ parent_names[0] = __clk_get_name(clk);
+ init.parent_names = parent_names;
+ init.num_parents = 1;
+
+ div1->reg = spicc->base + (u64) div1->reg;
+ div1->hw.init = &init;
+
+ clk = devm_clk_register(dev, &div1->hw);
+ if (WARN_ON(IS_ERR(clk)))
+ return PTR_ERR(clk);
+
+ mux_parent_names[1] = __clk_get_name(clk);
+
+ mux = &meson_spicc_sel;
+ snprintf(name, sizeof(name), "%s#_sel", dev_name(dev));
+ init.name = name;
+ init.ops = &clk_mux_ops;
+ init.parent_names = mux_parent_names;
+ init.num_parents = 2;
+ init.flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT;
+
+ mux->reg = spicc->base + (u64) mux->reg;
+ mux->hw.init = &init;
+
+ spicc->clk = devm_clk_register(dev, &mux->hw);
+ if (WARN_ON(IS_ERR(spicc->clk)))
+ return PTR_ERR(spicc->clk);
+
+ clk_set_parent(spicc->clk, clk);
+ return 0;
+}
+
static int meson_spicc_probe(struct platform_device *pdev)
{
struct spi_master *master;
@@ -557,6 +675,10 @@ static int meson_spicc_probe(struct platform_device *pdev)
goto out_master;
}
+ /* Set master mode and enable controller */
+ writel_relaxed(SPICC_ENABLE | SPICC_MODE_MASTER,
+ spicc->base + SPICC_CONREG);
+
/* Disable all IRQs */
writel_relaxed(0, spicc->base + SPICC_INTREG);
@@ -603,6 +725,12 @@ static int meson_spicc_probe(struct platform_device *pdev)
master->max_speed_hz = min_t(unsigned int, rate >> 1,
spicc->data->max_speed_hz);
+ ret = meson_spicc_clk_init(spicc);
+ if (ret) {
+ dev_err(&pdev->dev, "clock registration failed\n");
+ goto out_master;
+ }
+
ret = devm_spi_register_master(&pdev->dev, master);
if (!ret)
return 0;
@@ -634,6 +762,7 @@ static const struct meson_spicc_data meson_spicc_gx_data = {
static const struct meson_spicc_data meson_spicc_axg_data = {
.max_speed_hz = 80000000,
.has_oen = true,
+ .has_enhance_clk_div = true,
};
static const struct of_device_id meson_spicc_of_match[] = {
--
2.17.0
More information about the linux-arm-kernel
mailing list