EXYNOS: Add clock for SPI

Add api to calculate and set the clock for SPI channels

Signed-off-by: James Miller <jamesmiller@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Signed-off-by: Hatim Ali <hatim.rv@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

diff --git a/arch/arm/cpu/armv7/exynos/clock.c b/arch/arm/cpu/armv7/exynos/clock.c
index 40a8c7194648d9886af65b6e802b11faa90768e5..fe61f88af4954015b14c478ffa08c53bfc2fcd4b 100644 (file)
--- a/arch/arm/cpu/armv7/exynos/clock.c
+++ b/arch/arm/cpu/armv7/exynos/clock.c
@@ -25,6 +25,7 @@
 #include <asm/io.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/clk.h>
+#include <asm/arch/periph.h>
 
 /* Epll Clock division values to achive different frequency output */
 static struct set_epll_con_val exynos5_epll_div[] = {
@@ -804,6 +805,122 @@ int exynos5_set_i2s_clk_prescaler(unsigned int src_frq,
        return 0;
 }
 
+/**
+ * Linearly searches for the most accurate main and fine stage clock scalars
+ * (divisors) for a specified target frequency and scalar bit sizes by checking
+ * all multiples of main_scalar_bits values. Will always return scalars up to or
+ * slower than target.
+ *
+ * @param main_scalar_bits     Number of main scalar bits, must be > 0 and < 32
+ * @param fine_scalar_bits     Number of fine scalar bits, must be > 0 and < 32
+ * @param input_freq           Clock frequency to be scaled in Hz
+ * @param target_freq          Desired clock frequency in Hz
+ * @param best_fine_scalar     Pointer to store the fine stage divisor
+ *
+ * @return best_main_scalar    Main scalar for desired frequency or -1 if none
+ * found
+ */
+static int clock_calc_best_scalar(unsigned int main_scaler_bits,
+       unsigned int fine_scalar_bits, unsigned int input_rate,
+       unsigned int target_rate, unsigned int *best_fine_scalar)
+{
+       int i;
+       int best_main_scalar = -1;
+       unsigned int best_error = target_rate;
+       const unsigned int cap = (1 << fine_scalar_bits) - 1;
+       const unsigned int loops = 1 << main_scaler_bits;
+
+       debug("Input Rate is %u, Target is %u, Cap is %u\n", input_rate,
+                       target_rate, cap);
+
+       assert(best_fine_scalar != NULL);
+       assert(main_scaler_bits <= fine_scalar_bits);
+
+       *best_fine_scalar = 1;
+
+       if (input_rate == 0 || target_rate == 0)
+               return -1;
+
+       if (target_rate >= input_rate)
+               return 1;
+
+       for (i = 1; i <= loops; i++) {
+               const unsigned int effective_div = max(min(input_rate / i /
+                                                       target_rate, cap), 1);
+               const unsigned int effective_rate = input_rate / i /
+                                                       effective_div;
+               const int error = target_rate - effective_rate;
+
+               debug("%d|effdiv:%u, effrate:%u, error:%d\n", i, effective_div,
+                               effective_rate, error);
+
+               if (error >= 0 && error <= best_error) {
+                       best_error = error;
+                       best_main_scalar = i;
+                       *best_fine_scalar = effective_div;
+               }
+       }
+
+       return best_main_scalar;
+}
+
+static int exynos5_set_spi_clk(enum periph_id periph_id,
+                                       unsigned int rate)
+{
+       struct exynos5_clock *clk =
+               (struct exynos5_clock *)samsung_get_base_clock();
+       int main;
+       unsigned int fine;
+       unsigned shift, pre_shift;
+       unsigned mask = 0xff;
+       u32 *reg;
+
+       main = clock_calc_best_scalar(4, 8, 400000000, rate, &fine);
+       if (main < 0) {
+               debug("%s: Cannot set clock rate for periph %d",
+                               __func__, periph_id);
+               return -1;
+       }
+       main = main - 1;
+       fine = fine - 1;
+
+       switch (periph_id) {
+       case PERIPH_ID_SPI0:
+               reg = &clk->div_peric1;
+               shift = 0;
+               pre_shift = 8;
+               break;
+       case PERIPH_ID_SPI1:
+               reg = &clk->div_peric1;
+               shift = 16;
+               pre_shift = 24;
+               break;
+       case PERIPH_ID_SPI2:
+               reg = &clk->div_peric2;
+               shift = 0;
+               pre_shift = 8;
+               break;
+       case PERIPH_ID_SPI3:
+               reg = &clk->sclk_div_isp;
+               shift = 0;
+               pre_shift = 4;
+               break;
+       case PERIPH_ID_SPI4:
+               reg = &clk->sclk_div_isp;
+               shift = 12;
+               pre_shift = 16;
+               break;
+       default:
+               debug("%s: Unsupported peripheral ID %d\n", __func__,
+                     periph_id);
+               return -1;
+       }
+       clrsetbits_le32(reg, mask << shift, (main & mask) << shift);
+       clrsetbits_le32(reg, mask << pre_shift, (fine & mask) << pre_shift);
+
+       return 0;
+}
+
 unsigned long get_pll_clk(int pllreg)
 {
        if (cpu_is_exynos5())
@@ -876,6 +993,14 @@ void set_mipi_clk(void)
                exynos4_set_mipi_clk();
 }
 
+int set_spi_clk(int periph_id, unsigned int rate)
+{
+       if (cpu_is_exynos5())
+               return exynos5_set_spi_clk(periph_id, rate);
+       else
+               return 0;
+}
+
 int set_i2s_clk_prescaler(unsigned int src_frq, unsigned int dst_frq)
 {
 

diff --git a/arch/arm/include/asm/arch-exynos/clk.h b/arch/arm/include/asm/arch-exynos/clk.h
index 2bf2c10c44b891932fffbc4345f9f79d3df121cf..cd12323509a844c26c5de4c539b46bc854856d91 100644 (file)
--- a/arch/arm/include/asm/arch-exynos/clk.h
+++ b/arch/arm/include/asm/arch-exynos/clk.h
@@ -41,5 +41,6 @@ void set_mipi_clk(void);
 void set_i2s_clk_source(void);
 int set_i2s_clk_prescaler(unsigned int src_frq, unsigned int dst_frq);
 int set_epll_clk(unsigned long rate);
+int set_spi_clk(int periph_id, unsigned int rate);
 
 #endif