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Subject[PATCH 2/4] clk: ast2600: Add functionality to the APLL clock
Date
Register a clock with it's own operations to describe the APLL on
the AST2600. The clock is controlled by an SCU register containing
a multiplier and divider of the 25MHz input clock.
The functionality to change the APLL is necessary to finely control
the FSI bus frequency.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
drivers/clk/clk-ast2600.c | 177 +++++++++++++++++++++++++++++++++++---
1 file changed, 165 insertions(+), 12 deletions(-)

diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
index 177368cac6dd..a147dffbaccc 100644
--- a/drivers/clk/clk-ast2600.c
+++ b/drivers/clk/clk-ast2600.c
@@ -4,6 +4,7 @@

#define pr_fmt(fmt) "clk-ast2600: " fmt

+#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
@@ -15,7 +16,7 @@

#include "clk-aspeed.h"

-#define ASPEED_G6_NUM_CLKS 71
+#define ASPEED_G6_NUM_CLKS 72

#define ASPEED_G6_SILICON_REV 0x004

@@ -31,6 +32,7 @@
#define ASPEED_G6_CLK_SELECTION1 0x300
#define ASPEED_G6_CLK_SELECTION2 0x304
#define ASPEED_G6_CLK_SELECTION4 0x310
+#define ASPEED_G6_CLK_SELECTION5 0x314

#define ASPEED_HPLL_PARAM 0x200
#define ASPEED_APLL_PARAM 0x210
@@ -116,7 +118,7 @@ static const struct aspeed_gate_data aspeed_g6_gates[] = {
[ASPEED_CLK_GATE_UART11CLK] = { 59, -1, "uart11clk-gate", "uartx", 0 }, /* UART11 */
[ASPEED_CLK_GATE_UART12CLK] = { 60, -1, "uart12clk-gate", "uartx", 0 }, /* UART12 */
[ASPEED_CLK_GATE_UART13CLK] = { 61, -1, "uart13clk-gate", "uartx", 0 }, /* UART13 */
- [ASPEED_CLK_GATE_FSICLK] = { 62, 59, "fsiclk-gate", NULL, 0 }, /* FSI */
+ [ASPEED_CLK_GATE_FSICLK] = { 62, 59, "fsiclk-gate", "aplln", CLK_SET_RATE_PARENT }, /* FSI */
};

static const struct clk_div_table ast2600_eclk_div_table[] = {
@@ -187,24 +189,166 @@ static struct clk_hw *ast2600_calc_pll(const char *name, u32 val)
mult, div);
};

-static struct clk_hw *ast2600_calc_apll(const char *name, u32 val)
+/*
+ * APLL Frequency: F = 25MHz * (2 - od) * [(m + 2) / (n + 1)]
+ */
+static void ast2600_apll_get_params(unsigned int *div, unsigned int *mul)
{
- unsigned int mult, div;
+ u32 val = readl(scu_g6_base + ASPEED_APLL_PARAM);

if (val & BIT(20)) {
/* Pass through mode */
- mult = div = 1;
+ *mul = *div = 1;
} else {
- /* F = 25Mhz * (2-od) * [(m + 2) / (n + 1)] */
u32 m = (val >> 5) & 0x3f;
u32 od = (val >> 4) & 0x1;
u32 n = val & 0xf;

- mult = (2 - od) * (m + 2);
- div = n + 1;
+ *mul = (2 - od) * (m + 2);
+ *div = n + 1;
}
- return clk_hw_register_fixed_factor(NULL, name, "clkin", 0,
- mult, div);
+}
+
+static long ast2600_apll_best(unsigned long ul_rate, unsigned long ul_prate,
+ unsigned int *out_div, unsigned int *out_mul,
+ unsigned int *output_divider)
+{
+#define min_mult 2ULL
+#define max_mult 65ULL
+#define min_div 1ULL
+#define max_div 16ULL
+ int i;
+ unsigned int bod = 0;
+ unsigned long long rem = 1ULL;
+ unsigned long long brem = ~(0ULL);
+ unsigned long long bdiv = 1ULL;
+ unsigned long long tdiv;
+ unsigned long long bmul = 16ULL;
+ unsigned long long tmul;
+ long brate = -ERANGE;
+ unsigned long long trate;
+ unsigned long long rate = ul_rate;
+ unsigned long long prate = ul_prate;
+
+ for (i = 0; i < 2; ++i, prate *= 2ULL) {
+ for (tdiv = min_div; tdiv <= max_div; ++tdiv) {
+ tmul = DIV_ROUND_CLOSEST_ULL(rate * tdiv, prate);
+ if (tmul < min_mult || tmul > max_mult)
+ continue;
+
+ trate = DIV_ROUND_CLOSEST_ULL(prate * tmul, tdiv);
+ if (trate > rate)
+ rem = trate - rate;
+ else
+ rem = rate - trate;
+
+ if (rem < brem) {
+ bod = !i;
+ brem = rem;
+ bdiv = tdiv;
+ bmul = tmul;
+ brate = (long)trate;
+ }
+
+ if (!rem)
+ break;
+ }
+
+ if (!rem)
+ break;
+ }
+
+ if (out_div)
+ *out_div = (unsigned int)bdiv;
+
+ if (out_mul)
+ *out_mul = (unsigned int)bmul;
+
+ if (output_divider)
+ *output_divider = bod;
+
+ return brate;
+#undef min_mult
+#undef max_mult
+#undef min_div
+#undef max_div
+}
+
+static unsigned long ast2600_apll_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ unsigned int div;
+ unsigned int mul;
+ unsigned long long rate;
+ unsigned long long prate = (unsigned long long)parent_rate;
+
+ ast2600_apll_get_params(&div, &mul);
+
+ rate = DIV_ROUND_CLOSEST_ULL(prate * (unsigned long long)mul, div);
+ return (unsigned long)rate;
+}
+
+static long ast2600_apll_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ return ast2600_apll_best(rate, *parent_rate, NULL, NULL, NULL);
+}
+
+static int ast2600_apll_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ u32 val;
+ unsigned int od;
+ unsigned int div;
+ unsigned int mul;
+ long brate = ast2600_apll_best(rate, parent_rate, &div, &mul, &od);
+
+ if (brate < 0)
+ return brate;
+
+ val = readl(scu_g6_base + ASPEED_APLL_PARAM);
+ val &= ~0x7ff;
+ val |= (div - 1) & 0xf;
+ val |= ((mul - 2) & 0x3f) << 5;
+ if (od)
+ val |= 0x10;
+ writel(val, scu_g6_base + ASPEED_APLL_PARAM);
+
+ return 0;
+}
+
+static const struct clk_ops ast2600_apll_ops = {
+ .recalc_rate = ast2600_apll_recalc_rate,
+ .round_rate = ast2600_apll_round_rate,
+ .set_rate = ast2600_apll_set_rate,
+};
+
+static struct clk_hw *ast2600_create_apll(void)
+{
+ int rc;
+ const char *parent = "clkin";
+ struct clk_init_data init = {
+ .name = "apll",
+ .ops = &ast2600_apll_ops,
+ .parent_names = &parent,
+ .parent_data = NULL,
+ .parent_hws = NULL,
+ .num_parents = 1,
+ .flags = 0,
+ };
+ struct clk_hw *clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+
+ if (!clk)
+ return ERR_PTR(-ENOMEM);
+
+ clk->init = &init;
+ rc = of_clk_hw_register(NULL, clk);
+ if (rc) {
+ kfree(clk);
+ clk = ERR_PTR(rc);
+ }
+
+ return clk;
};

static u32 get_bit(u8 idx)
@@ -630,6 +774,16 @@ static int aspeed_g6_clk_probe(struct platform_device *pdev)
return PTR_ERR(hw);
aspeed_g6_clk_data->hws[ASPEED_CLK_ECLK] = hw;

+ hw = clk_hw_register_divider_table(dev, "aplln", "apll",
+ CLK_SET_RATE_PARENT,
+ scu_g6_base + ASPEED_G6_CLK_SELECTION5,
+ 28, 3, CLK_DIVIDER_READ_ONLY,
+ ast2600_eclk_div_table,
+ &aspeed_g6_clk_lock);
+ if (IS_ERR(hw))
+ return PTR_ERR(hw);
+ aspeed_g6_clk_data->hws[ASPEED_CLK_APLLN] = hw;
+
for (i = 0; i < ARRAY_SIZE(aspeed_g6_gates); i++) {
const struct aspeed_gate_data *gd = &aspeed_g6_gates[i];
u32 gate_flags;
@@ -710,8 +864,7 @@ static void __init aspeed_g6_cc(struct regmap *map)
regmap_read(map, ASPEED_EPLL_PARAM, &val);
aspeed_g6_clk_data->hws[ASPEED_CLK_EPLL] = ast2600_calc_pll("epll", val);

- regmap_read(map, ASPEED_APLL_PARAM, &val);
- aspeed_g6_clk_data->hws[ASPEED_CLK_APLL] = ast2600_calc_apll("apll", val);
+ aspeed_g6_clk_data->hws[ASPEED_CLK_APLL] = ast2600_create_apll();

/* Strap bits 12:11 define the AXI/AHB clock frequency ratio (aka HCLK)*/
regmap_read(map, ASPEED_G6_STRAP1, &val);
--
2.26.2
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